Add qtpy-rp2040 to TinyGo v0.25.0

2026-07-30 16:48:40 +00:00 · 2022-09-02 09:26:23 +09:00
158 changed files with 916 additions and 1529 deletions
@@ -118,7 +118,13 @@ jobs:
    steps:
      - test-linux:
          llvm: "14"
-    resource_class: large
+  test-llvm14-go119:
+    docker:
+      - image: golang:1.19beta1-buster
+    steps:
+      - test-linux:
+          llvm: "14"
+          fmt-check: false

 workflows:
  test-all:
@@ -126,3 +132,6 @@ workflows:
      # This tests our lowest supported versions of Go and LLVM, to make sure at
      # least the smoke tests still pass.
      - test-llvm14-go118
+      # This tests a beta version of Go. It should be removed once regular
+      # release builds are built using this version.
+      - test-llvm14-go119
@@ -16,6 +16,10 @@ jobs:
    name: build-macos
    runs-on: macos-11
    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.18.1'
      - name: Install Dependencies
        shell: bash
        run: |
@@ -31,13 +35,8 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
-      - name: Install Go
-        uses: actions/setup-go@v3
-        with:
-          go-version: '1.19'
-          cache: true
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-macos-v1
@@ -51,7 +50,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-macos-v1
@@ -69,7 +68,7 @@ jobs:
          make llvm-build
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-v4
@@ -105,17 +104,23 @@ jobs:
    name: homebrew-install
    runs-on: macos-latest
    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.18'
      - name: Install LLVM
        shell: bash
        run: |
          HOMEBREW_NO_AUTO_UPDATE=1 brew install llvm@14
      - name: Checkout
        uses: actions/checkout@v2
-      - name: Install Go
-        uses: actions/setup-go@v3
+      - name: Cache Go
+        uses: actions/cache@v2
        with:
-          go-version: '1.19'
-          cache: true
+          key: go-cache-macos-homebrew-v1-${{ hashFiles('go.mod') }}
+          path: |
+            ~/Library/Caches/go-build
+            ~/go/pkg/mod
      - name: Build TinyGo
        run: go install
      - name: Check binary
@@ -18,13 +18,14 @@ jobs:
    # statically linked binary.
    runs-on: ubuntu-latest
    container:
-      image: golang:1.19-alpine
+      image: alpine:3.16
    steps:
      - name: Install apk dependencies
-        # tar: needed for actions/cache@v3
+        # tar: needed for actions/cache@v2
        # git+openssh: needed for checkout (I think?)
+        # gcompat: needed for go binary
        # ruby: needed to install fpm
-        run: apk add tar git openssh make g++ ruby
+        run: apk add tar git openssh gcompat make g++ ruby
      - name: Work around CVE-2022-24765
        # We're not on a multi-user machine, so this is safe.
        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
@@ -32,15 +33,19 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.18.1'
      - name: Cache Go
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        with:
          key: go-cache-linux-alpine-v1-${{ hashFiles('go.mod') }}
          path: |
            ~/.cache/go-build
            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-alpine-v1
@@ -54,7 +59,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-alpine-v1
@@ -72,7 +77,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-binaryen
        with:
          key: binaryen-linux-alpine-v1
@@ -83,7 +88,7 @@ jobs:
          apk add cmake samurai python3
          make binaryen STATIC=1
      - name: Cache wasi-libc
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-linux-alpine-v1
@@ -116,10 +121,9 @@ jobs:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Install Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v2
        with:
-          go-version: '1.19'
-          cache: true
+          go-version: '1.18.1'
      - name: Install wasmtime
        run: |
          curl https://wasmtime.dev/install.sh -sSf | bash
@@ -169,10 +173,9 @@ jobs:
              simavr \
              ninja-build
      - name: Install Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v2
        with:
-          go-version: '1.19'
-          cache: true
+          go-version: '1.18.1'
      - name: Install Node.js
        uses: actions/setup-node@v2
        with:
@@ -181,8 +184,15 @@ jobs:
        run: |
          curl https://wasmtime.dev/install.sh -sSf | bash
          echo "$HOME/.wasmtime/bin" >> $GITHUB_PATH
+      - name: Cache Go
+        uses: actions/cache@v2
+        with:
+          key: go-cache-linux-asserts-v1-${{ hashFiles('go.mod') }}
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-asserts-v2
@@ -196,7 +206,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-asserts-v1
@@ -212,7 +222,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-binaryen
        with:
          key: binaryen-linux-asserts-v1
@@ -221,7 +231,7 @@ jobs:
        if: steps.cache-binaryen.outputs.cache-hit != 'true'
        run: make binaryen
      - name: Cache wasi-libc
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-linux-asserts-v5
@@ -269,12 +279,18 @@ jobs:
              g++-arm-linux-gnueabihf \
              libc6-dev-armhf-cross
      - name: Install Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v2
        with:
-          go-version: '1.19'
-          cache: true
+          go-version: '1.18.1'
+      - name: Cache Go
+        uses: actions/cache@v2
+        with:
+          key: go-cache-linux-arm-v2-${{ hashFiles('go.mod') }}
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-v2
@@ -288,7 +304,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-arm-v1
@@ -306,7 +322,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-binaryen
        with:
          key: binaryen-linux-arm-v1
@@ -369,12 +385,18 @@ jobs:
              libc6-dev-arm64-cross \
              ninja-build
      - name: Install Go
-        uses: actions/setup-go@v3
+        uses: actions/setup-go@v2
        with:
-          go-version: '1.19'
-          cache: true
+          go-version: '1.18.1'
+      - name: Cache Go
+        uses: actions/cache@v2
+        with:
+          key: go-cache-linux-arm64-v2-${{ hashFiles('go.mod') }}
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-linux-v1
@@ -388,7 +410,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-linux-arm64-v1
@@ -404,7 +426,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache Binaryen
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-binaryen
        with:
          key: binaryen-linux-arm64-v1
@@ -15,6 +15,10 @@ jobs:
  build-windows:
    runs-on: windows-2022
    steps:
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: '1.18.1'
      - uses: brechtm/setup-scoop@v2
        with:
          scoop_update: 'false'
@@ -26,13 +30,15 @@ jobs:
        uses: actions/checkout@v2
        with:
          submodules: true
-      - name: Install Go
-        uses: actions/setup-go@v3
+      - name: Cache Go
+        uses: actions/cache@v2
        with:
-          go-version: '1.19'
-          cache: true
+          key: go-cache-windows-v1-${{ hashFiles('go.mod') }}
+          path: |
+            ~/AppData/Local/go-build
+            ~/go/pkg/mod
      - name: Cache LLVM source
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-source
        with:
          key: llvm-source-14-windows-v2
@@ -46,7 +52,7 @@ jobs:
        if: steps.cache-llvm-source.outputs.cache-hit != 'true'
        run: make llvm-source
      - name: Cache LLVM build
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-llvm-build
        with:
          key: llvm-build-14-windows-v2
@@ -63,7 +69,7 @@ jobs:
          # Remove unnecessary object files (to reduce cache size).
          find llvm-build -name CMakeFiles -prune -exec rm -r '{}' \;
      - name: Cache wasi-libc sysroot
-        uses: actions/cache@v3
+        uses: actions/cache@v2
        id: cache-wasi-libc
        with:
          key: wasi-libc-sysroot-v4
@@ -1,5 +1,5 @@
 # tinygo-llvm stage obtains the llvm source for TinyGo
-FROM golang:1.19 AS tinygo-llvm
+FROM golang:1.18 AS tinygo-llvm

 RUN apt-get update && \
    apt-get install -y apt-utils make cmake clang-11 binutils-avr gcc-avr avr-libc ninja-build
@@ -326,14 +326,11 @@ TEST_PACKAGES_FAST += crypto/elliptic/internal/fiat
 endif

 # archive/zip requires os.ReadAt, which is not yet supported on windows
-# compress/flate appears to hang on wasi
-# compress/lzw appears to hang on wasi
-# crypto/hmac fails on wasi, it exits with a "slice out of range" panic
 # debug/plan9obj requires os.ReadAt, which is not yet supported on windows
-# io/ioutil requires os.ReadDir, which is not yet supported on windows or wasi
-# strconv requires recover() which is not yet supported on wasi
-# text/template/parse requires recover(), which is not yet supported on wasi
+# io/fs requires os.ReadDir, which is not yet supported on windows or wasi
 # testing/fstest requires os.ReadDir, which is not yet supported on windows or wasi
+# compress/flate fails windows go 1.18, https://github.com/tinygo-org/tinygo/issues/2762
+# compress/lzw fails windows go 1.18 wasi, https://github.com/tinygo-org/tinygo/issues/2762

 # Additional standard library packages that pass tests on individual platforms
 TEST_PACKAGES_LINUX := \
@@ -343,6 +340,7 @@ TEST_PACKAGES_LINUX := \
 	crypto/hmac \
 	debug/dwarf \
 	debug/plan9obj \
+	io/fs \
 	io/ioutil \
 	strconv \
 	testing/fstest \
@@ -351,12 +349,7 @@ TEST_PACKAGES_LINUX := \
 TEST_PACKAGES_DARWIN := $(TEST_PACKAGES_LINUX)

 TEST_PACKAGES_WINDOWS := \
-	compress/flate \
-	compress/lzw \
-	crypto/hmac \
-	strconv \
-	text/template/parse \
-	$(nil)
+	compress/lzw

 # Report platforms on which each standard library package is known to pass tests
 jointmp := $(shell echo /tmp/join.$$$$)
@@ -371,15 +364,12 @@ report-stdlib-tests-pass:
 # Standard library packages that pass tests quickly on the current platform
 ifeq ($(shell uname),Darwin)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_DARWIN)
-TEST_IOFS := true
 endif
 ifeq ($(shell uname),Linux)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_LINUX)
-TEST_IOFS := true
 endif
 ifeq ($(OS),Windows_NT)
 TEST_PACKAGES_HOST := $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_WINDOWS)
-TEST_IOFS := false
 endif

 # Test known-working standard library packages.
@@ -387,12 +377,6 @@ endif
 .PHONY: tinygo-test
 tinygo-test:
 	$(TINYGO) test $(TEST_PACKAGES_HOST) $(TEST_PACKAGES_SLOW)
-	@# io/fs requires os.ReadDir, not yet supported on windows or wasi. It also
-	@# requires a large stack-size. Hence, io/fs is only run conditionally.
-	@# For more details, see the comments on issue #3143.
-ifeq ($(TEST_IOFS),true)
-	$(TINYGO) test -stack-size=6MB io/fs
-endif
 tinygo-test-fast:
 	$(TINYGO) test $(TEST_PACKAGES_HOST)
 tinygo-bench:
@@ -402,9 +386,9 @@ tinygo-bench-fast:

 # Same thing, except for wasi rather than the current platform.
 tinygo-test-wasi:
-	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW) ./tests/runtime_wasi
+	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW)
 tinygo-test-wasi-fast:
-	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST) ./tests/runtime_wasi
+	$(TINYGO) test -target wasi $(TEST_PACKAGES_FAST)
 tinygo-bench-wasi:
 	$(TINYGO) test -target wasi -bench . $(TEST_PACKAGES_FAST) $(TEST_PACKAGES_SLOW)
 tinygo-bench-wasi-fast:
@@ -426,7 +410,6 @@ tinygo-baremetal:
 .PHONY: smoketest
 smoketest:
 	$(TINYGO) version
-	$(TINYGO) targets > /dev/null
 	# regression test for #2892
 	cd tests/testing/recurse && ($(TINYGO) test ./... > recurse.log && cat recurse.log && test $$(wc -l < recurse.log) = 2 && rm recurse.log)
 	# compile-only platform-independent examples
@@ -536,8 +519,6 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=feather-m4          examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=matrixportal-m4     examples/blinky1
-	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=pybadge             examples/blinky1
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=metro-m4-airlift    examples/blinky1
@@ -618,7 +599,7 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=challenger-rp2040    examples/blinky1
 	@$(MD5SUM) test.hex
-	$(TINYGO) build -size short -o test.hex -target=trinkey-qt2040      examples/temp
+	$(TINYGO) build -size short -o test.hex -target=trinkey-qt2040      examples/adc_rp2040
 	@$(MD5SUM) test.hex
 	# test pwm
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm
@@ -700,9 +681,7 @@ ifneq ($(XTENSA), 0)
 	$(TINYGO) build -size short -o test.bin -target mch2022             examples/serial
 	@$(MD5SUM) test.bin
 endif
-	$(TINYGO) build -size short -o test.bin -target=esp32c3             examples/serial
-	@$(MD5SUM) test.bin
-	$(TINYGO) build -size short -o test.bin -target=esp32c3-12f         examples/serial
+	$(TINYGO) build -size short -o test.bin -target=esp32c3           	examples/serial
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.bin -target=m5stamp-c3          examples/serial
 	@$(MD5SUM) test.bin
@@ -710,6 +689,8 @@ endif
 	@$(MD5SUM) test.bin
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex
+	$(TINYGO) build -size short -o test.hex -target=hifive1-qemu        examples/serial
+	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=maixbit             examples/blinky1
 	@$(MD5SUM) test.hex
 ifneq ($(WASM), 0)
@@ -125,7 +125,7 @@ The following 91 microcontroller boards are currently supported:
 * [Seeed LoRa-E5 Development Kit](https://www.seeedstudio.com/LoRa-E5-Dev-Kit-p-4868.html)
 * [Seeed Sipeed MAix BiT](https://www.seeedstudio.com/Sipeed-MAix-BiT-for-RISC-V-AI-IoT-p-2872.html)
 * [Seeed Wio Terminal](https://www.seeedstudio.com/Wio-Terminal-p-4509.html)
-* [SiFIve HiFive1 Rev B](https://www.sifive.com/boards/hifive1-rev-b)
+* [SiFIve HiFive1 Rev B](https://www.sifive.com/boards/hifive1)
 * [Sparkfun Thing Plus RP2040](https://www.sparkfun.com/products/17745)
 * [ST Micro "Nucleo" F103RB](https://www.st.com/en/evaluation-tools/nucleo-f103rb.html)
 * [ST Micro "Nucleo" F722ZE](https://www.st.com/en/evaluation-tools/nucleo-f722ze.html)
@@ -178,7 +178,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil

 		Scheduler:          config.Scheduler(),
 		AutomaticStackSize: config.AutomaticStackSize(),
-		DefaultStackSize:   config.StackSize(),
+		DefaultStackSize:   config.Target.DefaultStackSize,
 		NeedsStackObjects:  config.NeedsStackObjects(),
 		Debug:              true,
 	}
@@ -32,7 +32,6 @@ type cgoPackage struct {
 	errors          []error
 	currentDir      string // current working directory
 	packageDir      string // full path to the package to process
-	importPath      string
 	fset            *token.FileSet
 	tokenFiles      map[string]*token.File
 	definedGlobally map[string]ast.Node
@@ -40,15 +39,12 @@ type cgoPackage struct {
 	cflags          []string // CFlags from #cgo lines
 	ldflags         []string // LDFlags from #cgo lines
 	visitedFiles    map[string][]byte
-	cgoHeaders      []string
 }

 // cgoFile holds information only for a single Go file (with one or more
 // `import "C"` statements).
 type cgoFile struct {
 	*cgoPackage
-	file    *ast.File
-	index   int
 	defined map[string]ast.Node
 	names   map[string]clangCursor
 }
@@ -162,10 +158,9 @@ func GoBytes(ptr unsafe.Pointer, length C.int) []byte {
 // functions), the CFLAGS and LDFLAGS found in #cgo lines, and a map of file
 // hashes of the accessed C header files. If there is one or more error, it
 // returns these in the []error slice but still modifies the AST.
-func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cflags []string, clangHeaders string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
+func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string, clangHeaders string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
 	p := &cgoPackage{
 		currentDir:      dir,
-		importPath:      importPath,
 		fset:            fset,
 		tokenFiles:      map[string]*token.File{},
 		definedGlobally: map[string]ast.Node{},
@@ -215,13 +210,13 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 		}
 	}
 	// Patch some types, for example *C.char in C.CString.
-	cf := p.newCGoFile(nil, -1) // dummy *cgoFile for the walker
+	cf := p.newCGoFile()
 	astutil.Apply(p.generated, func(cursor *astutil.Cursor) bool {
 		return cf.walker(cursor, nil)
 	}, nil)

 	// Find `import "C"` C fragments in the file.
-	p.cgoHeaders = make([]string, len(files)) // combined CGo header fragment for each file
+	cgoHeaders := make([]string, len(files)) // combined CGo header fragment for each file
 	for i, f := range files {
 		var cgoHeader string
 		for i := 0; i < len(f.Decls); i++ {
@@ -280,7 +275,7 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 			cgoHeader += fragment
 		}

-		p.cgoHeaders[i] = cgoHeader
+		cgoHeaders[i] = cgoHeader
 	}

 	// Define CFlags that will be used while parsing the package.
@@ -294,7 +289,7 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 	}

 	// Retrieve types such as C.int, C.longlong, etc from C.
-	p.newCGoFile(nil, -1).readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
+	p.newCGoFile().readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
 		gen := &ast.GenDecl{
 			TokPos: token.NoPos,
 			Tok:    token.TYPE,
@@ -308,8 +303,8 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl

 	// Process CGo imports for each file.
 	for i, f := range files {
-		cf := p.newCGoFile(f, i)
-		cf.readNames(p.cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
+		cf := p.newCGoFile()
+		cf.readNames(cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
 			for _, name := range builtinAliases {
 				// Names such as C.int should not be obtained from C.
 				// This works around an issue in picolibc that has `#define int`
@@ -325,14 +320,12 @@ func Process(files []*ast.File, dir, importPath string, fset *token.FileSet, cfl
 	// Print the newly generated in-memory AST, for debugging.
 	//ast.Print(fset, p.generated)

-	return p.generated, p.cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
+	return p.generated, cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
 }

-func (p *cgoPackage) newCGoFile(file *ast.File, index int) *cgoFile {
+func (p *cgoPackage) newCGoFile() *cgoFile {
 	return &cgoFile{
 		cgoPackage: p,
-		file:       file,
-		index:      index,
 		defined:    make(map[string]ast.Node),
 		names:      make(map[string]clangCursor),
 	}
@@ -1124,11 +1117,8 @@ func (f *cgoFile) getASTDeclName(name string, found clangCursor, iscall bool) st
 		return alias
 	}
 	node := f.getASTDeclNode(name, found, iscall)
-	if node, ok := node.(*ast.FuncDecl); ok {
-		if !iscall {
-			return node.Name.Name + "$funcaddr"
-		}
-		return node.Name.Name
+	if _, ok := node.(*ast.FuncDecl); ok && !iscall {
+		return "C." + name + "$funcaddr"
 	}
 	return "C." + name
 }
@@ -1152,7 +1142,7 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			// Original cgo reports an error like
 			//   cgo: inconsistent definitions for C.myint
 			// which is far less helpful.
-			f.addError(getPos(node), name+" defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
+			f.addError(getPos(node), "defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
 		}
 		f.defined[name] = node
 		return node
@@ -1160,39 +1150,11 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as

 	// The declaration has no AST node. Create it now.
 	f.defined[name] = nil
-	node, extra := f.createASTNode(name, found)
+	node, elaboratedType := f.createASTNode(name, found)
 	f.defined[name] = node
+	f.definedGlobally[name] = node
 	switch node := node.(type) {
 	case *ast.FuncDecl:
-		if strings.HasPrefix(node.Doc.List[0].Text, "//export _Cgo_static_") {
-			// Static function. Only accessible in the current Go file.
-			globalName := strings.TrimPrefix(node.Doc.List[0].Text, "//export ")
-			// Make an alias. Normally this is done using the alias function
-			// attribute, but MacOS for some reason doesn't support this (even
-			// though the linker has support for aliases in the form of N_INDR).
-			// Therefore, create an actual function for MacOS.
-			var params []string
-			for _, param := range node.Type.Params.List {
-				params = append(params, param.Names[0].Name)
-			}
-			callInst := fmt.Sprintf("%s(%s);", name, strings.Join(params, ", "))
-			if node.Type.Results != nil {
-				callInst = "return " + callInst
-			}
-			aliasDeclaration := fmt.Sprintf(`
-#ifdef __APPLE__
-%s {
-	%s
-}
-#else
-extern __typeof(%s) %s __attribute__((alias(%#v)));
-#endif
-`, extra.(string), callInst, name, globalName, name)
-			f.cgoHeaders[f.index] += "\n\n" + aliasDeclaration
-		} else {
-			// Regular (non-static) function.
-			f.definedGlobally[name] = node
-		}
 		f.generated.Decls = append(f.generated.Decls, node)
 		// Also add a declaration like the following:
 		//   var C.foo$funcaddr unsafe.Pointer
@@ -1200,7 +1162,7 @@ extern __typeof(%s) %s __attribute__((alias(%#v)));
 			Tok: token.VAR,
 			Specs: []ast.Spec{
 				&ast.ValueSpec{
-					Names: []*ast.Ident{{Name: node.Name.Name + "$funcaddr"}},
+					Names: []*ast.Ident{{Name: "C." + name + "$funcaddr"}},
 					Type: &ast.SelectorExpr{
 						X:   &ast.Ident{Name: "unsafe"},
 						Sel: &ast.Ident{Name: "Pointer"},
@@ -1209,10 +1171,8 @@ extern __typeof(%s) %s __attribute__((alias(%#v)));
 			},
 		})
 	case *ast.GenDecl:
-		f.definedGlobally[name] = node
 		f.generated.Decls = append(f.generated.Decls, node)
 	case *ast.TypeSpec:
-		f.definedGlobally[name] = node
 		f.generated.Decls = append(f.generated.Decls, &ast.GenDecl{
 			Tok:   token.TYPE,
 			Specs: []ast.Spec{node},
@@ -1226,8 +1186,7 @@ extern __typeof(%s) %s __attribute__((alias(%#v)));

 	// If this is a struct or union it may need bitfields or union accessor
 	// methods.
-	switch elaboratedType := extra.(type) {
-	case *elaboratedTypeInfo:
+	if elaboratedType != nil {
 		// Add struct bitfields.
 		for _, bitfield := range elaboratedType.bitfields {
 			f.createBitfieldGetter(bitfield, "C."+name)
@@ -48,7 +48,7 @@ func TestCGo(t *testing.T) {
 			}

 			// Process the AST with CGo.
-			cgoAST, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", "main", fset, cflags, "")
+			cgoAST, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", fset, cflags, "")

 			// Check the AST for type errors.
 			var typecheckErrors []error
@@ -4,9 +4,7 @@ package cgo
 // modification. It does not touch the AST itself.

 import (
-	"crypto/sha256"
 	"crypto/sha512"
-	"encoding/hex"
 	"fmt"
 	"go/ast"
 	"go/scanner"
@@ -45,8 +43,6 @@ typedef struct {
 GoCXCursor tinygo_clang_getTranslationUnitCursor(CXTranslationUnit tu);
 unsigned tinygo_clang_visitChildren(GoCXCursor parent, CXCursorVisitor visitor, CXClientData client_data);
 CXString tinygo_clang_getCursorSpelling(GoCXCursor c);
-CXString tinygo_clang_getCursorPrettyPrinted(GoCXCursor c, CXPrintingPolicy Policy);
-CXPrintingPolicy tinygo_clang_getCursorPrintingPolicy(GoCXCursor c);
 enum CXCursorKind tinygo_clang_getCursorKind(GoCXCursor c);
 CXType tinygo_clang_getCursorType(GoCXCursor c);
 GoCXCursor tinygo_clang_getTypeDeclaration(CXType t);
@@ -54,7 +50,6 @@ CXType tinygo_clang_getTypedefDeclUnderlyingType(GoCXCursor c);
 CXType tinygo_clang_getCursorResultType(GoCXCursor c);
 int tinygo_clang_Cursor_getNumArguments(GoCXCursor c);
 GoCXCursor tinygo_clang_Cursor_getArgument(GoCXCursor c, unsigned i);
-enum CX_StorageClass tinygo_clang_Cursor_getStorageClass(GoCXCursor c);
 CXSourceLocation tinygo_clang_getCursorLocation(GoCXCursor c);
 CXSourceRange tinygo_clang_getCursorExtent(GoCXCursor c);
 CXTranslationUnit tinygo_clang_Cursor_getTranslationUnit(GoCXCursor c);
@@ -194,7 +189,7 @@ func (f *cgoFile) readNames(fragment string, cflags []string, filename string, c

 // Convert the AST node under the given Clang cursor to a Go AST node and return
 // it.
-func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
+func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaboratedTypeInfo) {
 	kind := C.tinygo_clang_getCursorKind(c)
 	pos := f.getCursorPosition(c)
 	switch kind {
@@ -205,43 +200,19 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			Kind: ast.Fun,
 			Name: "C." + name,
 		}
-		exportName := name
-		localName := name
-		var stringSignature string
-		if C.tinygo_clang_Cursor_getStorageClass(c) == C.CX_SC_Static {
-			// A static function is assigned a globally unique symbol name based
-			// on the file path (like _Cgo_static_2d09198adbf58f4f4655_foo) and
-			// has a different Go name in the form of C.foo!symbols.go instead
-			// of just C.foo.
-			path := f.importPath + "/" + filepath.Base(f.fset.File(f.file.Pos()).Name())
-			staticIDBuf := sha256.Sum256([]byte(path))
-			staticID := hex.EncodeToString(staticIDBuf[:10])
-			exportName = "_Cgo_static_" + staticID + "_" + name
-			localName = name + "!" + filepath.Base(path)
-
-			// Create a signature. This is necessary for MacOS to forward the
-			// call, because MacOS doesn't support aliases like ELF and PE do.
-			// (There is N_INDR but __attribute__((alias("..."))) doesn't work).
-			policy := C.tinygo_clang_getCursorPrintingPolicy(c)
-			defer C.clang_PrintingPolicy_dispose(policy)
-			C.clang_PrintingPolicy_setProperty(policy, C.CXPrintingPolicy_TerseOutput, 1)
-			stringSignature = getString(C.tinygo_clang_getCursorPrettyPrinted(c, policy))
-			stringSignature = strings.Replace(stringSignature, " "+name+"(", " "+exportName+"(", 1)
-			stringSignature = strings.TrimPrefix(stringSignature, "static ")
-		}
 		args := make([]*ast.Field, numArgs)
 		decl := &ast.FuncDecl{
 			Doc: &ast.CommentGroup{
 				List: []*ast.Comment{
 					{
 						Slash: pos - 1,
-						Text:  "//export " + exportName,
+						Text:  "//export " + name,
 					},
 				},
 			},
 			Name: &ast.Ident{
 				NamePos: pos,
-				Name:    "C." + localName,
+				Name:    "C." + name,
 				Obj:     obj,
 			},
 			Type: &ast.FuncType{
@@ -292,7 +263,7 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 			}
 		}
 		obj.Decl = decl
-		return decl, stringSignature
+		return decl, nil
 	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
 		typ := f.makeASTRecordType(c, pos)
 		typeName := "C." + name
@@ -17,14 +17,6 @@ CXString tinygo_clang_getCursorSpelling(CXCursor c) {
 	return clang_getCursorSpelling(c);
 }

-CXString tinygo_clang_getCursorPrettyPrinted(CXCursor c, CXPrintingPolicy policy) {
-	return clang_getCursorPrettyPrinted(c, policy);
-}
-
-CXPrintingPolicy tinygo_clang_getCursorPrintingPolicy(CXCursor c) {
-	return clang_getCursorPrintingPolicy(c);
-}
-
 enum CXCursorKind tinygo_clang_getCursorKind(CXCursor c) {
 	return clang_getCursorKind(c);
 }
@@ -53,10 +45,6 @@ CXCursor tinygo_clang_Cursor_getArgument(CXCursor c, unsigned i) {
 	return clang_Cursor_getArgument(c, i);
 }

-enum CX_StorageClass tinygo_clang_Cursor_getStorageClass(CXCursor c) {
-	return clang_Cursor_getStorageClass(c);
-}
-
 CXSourceLocation tinygo_clang_getCursorLocation(CXCursor c) {
 	return clang_getCursorLocation(c);
 }
@@ -5,7 +5,6 @@ package main
 int foo(int a, int b);
 void variadic0();
 void variadic2(int x, int y, ...);
-static void staticfunc(int x);

 // Global variable signatures.
 extern int someValue;
@@ -17,7 +16,6 @@ func accessFunctions() {
 	C.foo(3, 4)
 	C.variadic0()
 	C.variadic2(3, 5)
-	C.staticfunc(3)
 }

 func accessGlobals() {
@@ -55,10 +55,5 @@ func C.variadic2(x C.int, y C.int)

 var C.variadic2$funcaddr unsafe.Pointer

-//export _Cgo_static_173c95a79b6df1980521_staticfunc
-func C.staticfunc!symbols.go(x C.int)
-
-var C.staticfunc!symbols.go$funcaddr unsafe.Pointer
-
 //go:extern someValue
 var C.someValue C.int
@@ -175,15 +175,6 @@ func (c *Config) AutomaticStackSize() bool {
 	return false
 }

-// StackSize returns the default stack size to be used for goroutines, if the
-// stack size could not be determined automatically at compile time.
-func (c *Config) StackSize() uint64 {
-	if c.Options.StackSize != 0 {
-		return c.Options.StackSize
-	}
-	return c.Target.DefaultStackSize
-}
-
 // UseThinLTO returns whether ThinLTO should be used for the given target. Some
 // targets (such as wasm) are not yet supported.
 // We should try and remove as many exceptions as possible in the future, so
@@ -466,14 +457,7 @@ func (c *Config) OpenOCDConfiguration() (args []string, err error) {
 		args = append(args, "-c", cmd)
 	}
 	if c.Target.OpenOCDTransport != "" {
-		transport := c.Target.OpenOCDTransport
-		if transport == "swd" {
-			switch openocdInterface {
-			case "stlink-dap":
-				transport = "dapdirect_swd"
-			}
-		}
-		args = append(args, "-c", "transport select "+transport)
+		args = append(args, "-c", "transport select "+c.Target.OpenOCDTransport)
 	}
 	args = append(args, "-f", "target/"+c.Target.OpenOCDTarget+".cfg")
 	return args, nil
@@ -28,7 +28,6 @@ type Options struct {
 	GC              string
 	PanicStrategy   string
 	Scheduler       string
-	StackSize       uint64 // goroutine stack size (if none could be automatically determined)
 	Serial          string
 	Work            bool // -work flag to print temporary build directory
 	InterpTimeout   time.Duration
@@ -50,8 +49,6 @@ type Options struct {
 	LLVMFeatures    string
 	Directory       string
 	PrintJSON       bool
-	Monitor         bool
-	BaudRate        int
 }

 // Verify performs a validation on the given options, raising an error if options are not valid.
@@ -65,7 +65,7 @@ type TargetSpec struct {
 }

 // overrideProperties overrides all properties that are set in child into itself using reflection.
-func (spec *TargetSpec) overrideProperties(child *TargetSpec) error {
+func (spec *TargetSpec) overrideProperties(child *TargetSpec) {
 	specType := reflect.TypeOf(spec).Elem()
 	specValue := reflect.ValueOf(spec).Elem()
 	childValue := reflect.ValueOf(child).Elem()
@@ -95,15 +95,14 @@ func (spec *TargetSpec) overrideProperties(child *TargetSpec) error {
 				for j := i + 1; j < dst.Len(); j++ {
 					w := dst.Index(j).String()
 					if v == w {
-						return fmt.Errorf("duplicate value '%s' in field %s", v, field.Name)
+						panic("duplicate value '" + v + "' in field : " + field.Name)
 					}
 				}
 			}
 		default:
-			return fmt.Errorf("unknown field type: %s", kind)
+			panic("unknown field type : " + kind.String())
 		}
 	}
-	return nil
 }

 // load reads a target specification from the JSON in the given io.Reader. It
@@ -118,10 +117,10 @@ func (spec *TargetSpec) load(r io.Reader) error {
 }

 // loadFromGivenStr loads the TargetSpec from the given string that could be:
-//   - targets/ directory inside the compiler sources
-//   - a relative or absolute path to custom (project specific) target specification .json file;
-//     the Inherits[] could contain the files from target folder (ex. stm32f4disco)
-//     as well as path to custom files (ex. myAwesomeProject.json)
+// - targets/ directory inside the compiler sources
+// - a relative or absolute path to custom (project specific) target specification .json file;
+//   the Inherits[] could contain the files from target folder (ex. stm32f4disco)
+//   as well as path to custom files (ex. myAwesomeProject.json)
 func (spec *TargetSpec) loadFromGivenStr(str string) error {
 	path := ""
 	if strings.HasSuffix(str, ".json") {
@@ -151,17 +150,11 @@ func (spec *TargetSpec) resolveInherits() error {
 		if err != nil {
 			return err
 		}
-		err = newSpec.overrideProperties(subtarget)
-		if err != nil {
-			return err
-		}
+		newSpec.overrideProperties(subtarget)
 	}

 	// When all properties are loaded, make sure they are properly inherited.
-	err := newSpec.overrideProperties(spec)
-	if err != nil {
-		return err
-	}
+	newSpec.overrideProperties(spec)
 	*spec = *newSpec

 	return nil
@@ -228,7 +221,7 @@ func LoadTarget(options *Options) (*TargetSpec, error) {
 	// it includes all parents as specified in the "inherits" key.
 	err = spec.resolveInherits()
 	if err != nil {
-		return nil, fmt.Errorf("%s : %w", options.Target, err)
+		return nil, err
 	}

 	if spec.Scheduler == "asyncify" {
@@ -79,7 +79,7 @@ func TestCompiler(t *testing.T) {
 				RelocationModel:    config.RelocationModel(),
 				Scheduler:          config.Scheduler(),
 				AutomaticStackSize: config.AutomaticStackSize(),
-				DefaultStackSize:   config.StackSize(),
+				DefaultStackSize:   config.Target.DefaultStackSize,
 				NeedsStackObjects:  config.NeedsStackObjects(),
 			}
 			machine, err := NewTargetMachine(compilerConfig)
@@ -163,20 +163,18 @@ func (c *compilerContext) getFunction(fn *ssa.Function) llvm.Value {
 	// External/exported functions may not retain pointer values.
 	// https://golang.org/cmd/cgo/#hdr-Passing_pointers
 	if info.exported {
-		if c.archFamily() == "wasm32" {
-			// We need to add the wasm-import-module and the wasm-import-name
-			// attributes.
-			module := info.module
-			if module == "" {
-				module = "env"
-			}
-			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-module", module))
+		// Set the wasm-import-module attribute if the function's module is set.
+		if info.module != "" {

-			name := info.importName
-			if name == "" {
-				name = info.linkName
+			// We need to add the wasm-import-module and the wasm-import-name
+			wasmImportModuleAttr := c.ctx.CreateStringAttribute("wasm-import-module", info.module)
+			llvmFn.AddFunctionAttr(wasmImportModuleAttr)
+
+			// Add the Wasm Import Name, if we are a named wasm import
+			if info.importName != "" {
+				wasmImportNameAttr := c.ctx.CreateStringAttribute("wasm-import-name", info.importName)
+				llvmFn.AddFunctionAttr(wasmImportNameAttr)
 			}
-			llvmFn.AddFunctionAttr(c.ctx.CreateStringAttribute("wasm-import-name", name))
 		}
 		nocaptureKind := llvm.AttributeKindID("nocapture")
 		nocapture := c.ctx.CreateEnumAttribute(nocaptureKind, 0)
@@ -62,7 +62,7 @@ declare void @main.undefinedFunctionNotInSection(i8*) #0

 attributes #0 = { "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #1 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" "wasm-import-module"="env" "wasm-import-name"="extern_func" }
+attributes #2 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="extern_func" }
 attributes #3 = { inlinehint nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
 attributes #4 = { noinline nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" }
-attributes #5 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" "wasm-import-module"="env" "wasm-import-name"="exportedFunctionInSection" }
+attributes #5 = { nounwind "target-features"="+bulk-memory,+nontrapping-fptoint,+sign-ext" "wasm-export-name"="exportedFunctionInSection" }
@@ -9,10 +9,8 @@ require (
 	github.com/chromedp/chromedp v0.7.6
 	github.com/gofrs/flock v0.8.1
 	github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf
-	github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf
 	github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892
 	github.com/mattn/go-colorable v0.1.8
-	github.com/mattn/go-tty v0.0.4
 	go.bug.st/serial v1.3.5
 	golang.org/x/sys v0.0.0-20220829200755-d48e67d00261
 	golang.org/x/tools v0.1.11
@@ -12,6 +12,7 @@ github.com/chromedp/sysutil v1.0.0/go.mod h1:kgWmDdq8fTzXYcKIBqIYvRRTnYb9aNS9moA
 github.com/creack/goselect v0.1.2 h1:2DNy14+JPjRBgPzAd1thbQp4BSIihxcBf0IXhQXDRa0=
 github.com/creack/goselect v0.1.2/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
 github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
 github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
@@ -22,47 +23,44 @@ github.com/gofrs/flock v0.8.1 h1:+gYjHKf32LDeiEEFhQaotPbLuUXjY5ZqxKgXy7n59aw=
 github.com/gofrs/flock v0.8.1/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf h1:7+FW5aGwISbqUtkfmIpZJGRgNFg2ioYPvFaUxdqpDsg=
 github.com/google/shlex v0.0.0-20181106134648-c34317bd91bf/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE=
-github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf h1:FtEj8sfIcaaBfAKrE1Cwb61YDtYq9JxChK1c7AKce7s=
-github.com/inhies/go-bytesize v0.0.0-20220417184213-4913239db9cf/go.mod h1:yrqSXGoD/4EKfF26AOGzscPOgTTJcyAwM2rpixWT+t4=
 github.com/josharian/intern v1.0.0 h1:vlS4z54oSdjm0bgjRigI+G1HpF+tI+9rE5LLzOg8HmY=
 github.com/josharian/intern v1.0.0/go.mod h1:5DoeVV0s6jJacbCEi61lwdGj/aVlrQvzHFFd8Hwg//Y=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
 github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892 h1:6J+qramlHVLmiBOgRiBOnQkno8uprqG6YFFQTt6uYIw=
 github.com/marcinbor85/gohex v0.0.0-20200531091804-343a4b548892/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
-github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-colorable v0.1.8 h1:c1ghPdyEDarC70ftn0y+A/Ee++9zz8ljHG1b13eJ0s8=
 github.com/mattn/go-colorable v0.1.8/go.mod h1:u6P/XSegPjTcexA+o6vUJrdnUu04hMope9wVRipJSqc=
-github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
-github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcMEpPG5Rm84=
 github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
-github.com/mattn/go-runewidth v0.0.7/go.mod h1:H031xJmbD/WCDINGzjvQ9THkh0rPKHF+m2gUSrubnMI=
-github.com/mattn/go-tty v0.0.4 h1:NVikla9X8MN0SQAqCYzpGyXv0jY7MNl3HOWD2dkle7E=
-github.com/mattn/go-tty v0.0.4/go.mod h1:u5GGXBtZU6RQoKV8gY5W6UhMudbR5vXnUe7j3pxse28=
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5 h1:1SoBaSPudixRecmlHXb/GxmaD3fLMtHIDN13QujwQuc=
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5/go.mod h1:nZgzbfBr3hhjoZnS66nKrHmduYNpc34ny7RK4z5/HM0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+go.bug.st/serial v1.1.3 h1:YEBxJa9pKS9Wdg46B/jiaKbvvbUrjhZZZITfJHEJhaE=
+go.bug.st/serial v1.1.3/go.mod h1:8TT7u/SwwNIpJ8QaG4s+HTjFt9ReXs2cdOU7ZEk50Dk=
 go.bug.st/serial v1.3.5 h1:k50SqGZCnHZ2MiBQgzccXWG+kd/XpOs1jUljpDDKzaE=
 go.bug.st/serial v1.3.5/go.mod h1:z8CesKorE90Qr/oRSJiEuvzYRKol9r/anJZEb5kt304=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
-golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200909081042-eff7692f9009/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201207223542-d4d67f95c62d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20211124211545-fe61309f8881/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 h1:XfKQ4OlFl8okEOr5UvAqFRVj8pY/4yfcXrddB8qAbU0=
+golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220829200755-d48e67d00261 h1:v6hYoSR9T5oet+pMXwUWkbiVqx/63mlHjefrHmxwfeY=
 golang.org/x/sys v0.0.0-20220829200755-d48e67d00261/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/tools v0.1.11 h1:loJ25fNOEhSXfHrpoGj91eCUThwdNX6u24rO1xnNteY=
 golang.org/x/tools v0.1.11/go.mod h1:SgwaegtQh8clINPpECJMqnxLv9I09HLqnW3RMqW0CA4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 tinygo.org/x/go-llvm v0.0.0-20220802112859-5bb0b77907a7 h1:nSLR52mUw7DPQQVA3ZJFH63zjU4ME84fKiin6mdnYWc=
 tinygo.org/x/go-llvm v0.0.0-20220802112859-5bb0b77907a7/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=
@@ -369,11 +369,6 @@ func (r *runner) run(fn *function, params []value, parentMem *memoryView, indent
 				nBytes := uint32(operands[3].Uint())
 				dstObj := mem.getWritable(dst.index())
 				dstBuf := dstObj.buffer.asRawValue(r)
-				if mem.get(src.index()).buffer == nil {
-					// Looks like the source buffer is not defined.
-					// This can happen with //extern or //go:embed.
-					return nil, mem, r.errorAt(inst, errUnsupportedRuntimeInst)
-				}
 				srcBuf := mem.get(src.index()).buffer.asRawValue(r)
 				copy(dstBuf.buf[dst.offset():dst.offset()+nBytes], srcBuf.buf[src.offset():])
 				dstObj.buffer = dstBuf
@@ -440,7 +440,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 		var initialCFlags []string
 		initialCFlags = append(initialCFlags, p.program.config.CFlags()...)
 		initialCFlags = append(initialCFlags, "-I"+p.Dir)
-		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.ImportPath, p.program.fset, initialCFlags, p.program.clangHeaders)
+		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.program.fset, initialCFlags, p.program.clangHeaders)
 		p.CFlags = append(initialCFlags, cflags...)
 		p.CGoHeaders = headerCode
 		for path, hash := range accessedFiles {
@@ -26,7 +26,6 @@ import (
 	"time"

 	"github.com/google/shlex"
-	"github.com/inhies/go-bytesize"
 	"github.com/mattn/go-colorable"
 	"github.com/tinygo-org/tinygo/builder"
 	"github.com/tinygo-org/tinygo/compileopts"
@@ -244,36 +243,17 @@ func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options
 		// Tests are always run in the package directory.
 		cmd.Dir = result.MainDir

-		// wasmtime is the default emulator used for `-target=wasi`. wasmtime
-		// is a WebAssembly runtime CLI with WASI enabled by default. However,
-		// only stdio are allowed by default. For example, while STDOUT routes
-		// to the host, other files don't. It also does not inherit environment
-		// variables from the host. Some tests read testdata files, often from
-		// outside the package directory. Other tests require temporary
-		// writeable directories. We allow this by adding wasmtime flags below.
+		// Wasmtime needs a few extra flags to work.
 		if config.EmulatorName() == "wasmtime" {
-			// At this point, The current working directory is at the package
-			// directory. Ex. $GOROOT/src/compress/flate for compress/flate.
-			// buildAndRun has already added arguments for wasmtime, that allow
-			// read-access to files such as "testdata/huffman-zero.in".
-			//
-			// Ex. main(.wasm) --dir=. -- -test.v
-
-			// Below adds additional wasmtime flags in case a test reads files
-			// outside its directory, like "../testdata/e.txt". This allows any
-			// relative directory up to the module root, even if the test never
-			// reads any files.
-			//
-			// Ex. --dir=.. --dir=../.. --dir=../../..
+			// Add directories to the module root, but skip the current working
+			// directory which is already added by buildAndRun.
 			dirs := dirsToModuleRoot(result.MainDir, result.ModuleRoot)
 			var args []string
 			for _, d := range dirs[1:] {
 				args = append(args, "--dir="+d)
 			}

-			// Some tests create temp directories using os.MkdirTemp or via
-			// t.TempDir(). Create a writeable directory and map it to the
-			// default tempDir environment variable: TMPDIR.
+			// create a new temp directory just for this run, announce it to os.TempDir() via TMPDIR
 			tmpdir, err := os.MkdirTemp("", "tinygotmp")
 			if err != nil {
 				return fmt.Errorf("failed to create temporary directory: %w", err)
@@ -282,8 +262,7 @@ func Test(pkgName string, stdout, stderr io.Writer, options *compileopts.Options
 			// TODO: add option to not delete temp dir for debugging?
 			defer os.RemoveAll(tmpdir)

-			// The below re-organizes the arguments so that the current
-			// directory is added last.
+			// Insert new argments at the front of the command line argments.
 			args = append(args, cmd.Args[1:]...)
 			cmd.Args = append(cmd.Args[:1:1], args...)
 		}
@@ -423,6 +402,7 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
+			return nil
 		case "msd":
 			switch fileExt {
 			case ".uf2":
@@ -430,11 +410,13 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 				if err != nil {
 					return &commandError{"failed to flash", result.Binary, err}
 				}
+				return nil
 			case ".hex":
 				err := flashHexUsingMSD(config.Target.FlashVolume, result.Binary, config.Options)
 				if err != nil {
 					return &commandError{"failed to flash", result.Binary, err}
 				}
+				return nil
 			default:
 				return errors.New("mass storage device flashing currently only supports uf2 and hex")
 			}
@@ -455,6 +437,7 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
+			return nil
 		case "bmp":
 			gdb, err := config.Target.LookupGDB()
 			if err != nil {
@@ -473,13 +456,10 @@ func Flash(pkgName, port string, options *compileopts.Options) error {
 			if err != nil {
 				return &commandError{"failed to flash", result.Binary, err}
 			}
+			return nil
 		default:
 			return fmt.Errorf("unknown flash method: %s", flashMethod)
 		}
-		if options.Monitor {
-			return Monitor("", options)
-		}
-		return nil
 	})
 }

@@ -998,8 +978,7 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 			preferredPortIDs = append(preferredPortIDs, [2]uint16{uint16(vid), uint16(pid)})
 		}

-		var primaryPorts []string   // ports picked from preferred USB VID/PID
-		var secondaryPorts []string // other ports (as a fallback)
+		var primaryPorts []string // ports picked from preferred USB VID/PID
 		for _, p := range portsList {
 			if !p.IsUSB {
 				continue
@@ -1021,8 +1000,6 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 					continue
 				}
 			}
-
-			secondaryPorts = append(secondaryPorts, p.Name)
 		}
 		if len(primaryPorts) == 1 {
 			// There is exactly one match in the set of preferred ports. Use
@@ -1034,10 +1011,18 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 			// one device of the same type are connected (e.g. two Arduino
 			// Unos).
 			ports = primaryPorts
-		} else {
-			// No preferred ports found. Fall back to other serial ports
-			// available in the system.
-			ports = secondaryPorts
+		}
+
+		if len(ports) == 0 {
+			// fallback
+			switch runtime.GOOS {
+			case "darwin":
+				ports, err = filepath.Glob("/dev/cu.usb*")
+			case "linux":
+				ports, err = filepath.Glob("/dev/ttyACM*")
+			case "windows":
+				ports, err = serial.GetPortsList()
+			}
 		}
 	default:
 		return "", errors.New("unable to search for a default USB device to be flashed on this OS")
@@ -1052,9 +1037,7 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 	}

 	if len(portCandidates) == 0 {
-		if len(usbInterfaces) > 0 {
-			return "", errors.New("unable to search for a default USB device - use -port flag, available ports are " + strings.Join(ports, ", "))
-		} else if len(ports) == 1 {
+		if len(ports) == 1 {
 			return ports[0], nil
 		} else {
 			return "", errors.New("multiple serial ports available - use -port flag, available ports are " + strings.Join(ports, ", "))
@@ -1119,7 +1102,6 @@ func usage(command string) {
 		fmt.Fprintln(os.Stderr, "  flash:   compile and flash to the device")
 		fmt.Fprintln(os.Stderr, "  gdb:     run/flash and immediately enter GDB")
 		fmt.Fprintln(os.Stderr, "  lldb:    run/flash and immediately enter LLDB")
-		fmt.Fprintln(os.Stderr, "  monitor: open communication port")
 		fmt.Fprintln(os.Stderr, "  env:     list environment variables used during build")
 		fmt.Fprintln(os.Stderr, "  list:    run go list using the TinyGo root")
 		fmt.Fprintln(os.Stderr, "  clean:   empty cache directory ("+goenv.Get("GOCACHE")+")")
@@ -1316,12 +1298,6 @@ func main() {
 	var tags buildutil.TagsFlag
 	flag.Var(&tags, "tags", "a space-separated list of extra build tags")
 	target := flag.String("target", "", "chip/board name or JSON target specification file")
-	var stackSize uint64
-	flag.Func("stack-size", "goroutine stack size (if unknown at compile time)", func(s string) error {
-		size, err := bytesize.Parse(s)
-		stackSize = uint64(size)
-		return err
-	})
 	printSize := flag.String("size", "", "print sizes (none, short, full)")
 	printStacks := flag.Bool("print-stacks", false, "print stack sizes of goroutines")
 	printAllocsString := flag.String("print-allocs", "", "regular expression of functions for which heap allocations should be printed")
@@ -1336,8 +1312,6 @@ func main() {
 	wasmAbi := flag.String("wasm-abi", "", "WebAssembly ABI conventions: js (no i64 params) or generic")
 	llvmFeatures := flag.String("llvm-features", "", "comma separated LLVM features to enable")
 	cpuprofile := flag.String("cpuprofile", "", "cpuprofile output")
-	monitor := flag.Bool("monitor", false, "enable serial monitor")
-	baudrate := flag.Int("baudrate", 115200, "baudrate of serial monitor")

 	var flagJSON, flagDeps, flagTest bool
 	if command == "help" || command == "list" || command == "info" || command == "build" {
@@ -1404,7 +1378,6 @@ func main() {
 		GOARCH:          goenv.Get("GOARCH"),
 		GOARM:           goenv.Get("GOARM"),
 		Target:          *target,
-		StackSize:       stackSize,
 		Opt:             *opt,
 		GC:              *gc,
 		PanicStrategy:   *panicStrategy,
@@ -1427,8 +1400,6 @@ func main() {
 		OpenOCDCommands: ocdCommands,
 		LLVMFeatures:    *llvmFeatures,
 		PrintJSON:       flagJSON,
-		Monitor:         *monitor,
-		BaudRate:        *baudrate,
 	}
 	if *printCommands {
 		options.PrintCommands = printCommand
@@ -1619,9 +1590,6 @@ func main() {
 			fmt.Println("FAIL")
 			os.Exit(1)
 		}
-	case "monitor":
-		err := Monitor(*port, options)
-		handleCompilerError(err)
 	case "targets":
 		dir := filepath.Join(goenv.Get("TINYGOROOT"), "targets")
 		entries, err := ioutil.ReadDir(dir)
@@ -1,106 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"os"
-	"os/signal"
-	"time"
-
-	"github.com/mattn/go-tty"
-	"github.com/tinygo-org/tinygo/builder"
-	"github.com/tinygo-org/tinygo/compileopts"
-	"go.bug.st/serial"
-)
-
-// Monitor connects to the given port and reads/writes the serial port.
-func Monitor(port string, options *compileopts.Options) error {
-	config, err := builder.NewConfig(options)
-	if err != nil {
-		return err
-	}
-
-	wait := 300
-	for i := 0; i <= wait; i++ {
-		port, err = getDefaultPort(port, config.Target.SerialPort)
-		if err != nil {
-			if i < wait {
-				time.Sleep(10 * time.Millisecond)
-				continue
-			}
-			return err
-		}
-		break
-	}
-
-	br := options.BaudRate
-	if br <= 0 {
-		br = 115200
-	}
-
-	wait = 300
-	var p serial.Port
-	for i := 0; i <= wait; i++ {
-		p, err = serial.Open(port, &serial.Mode{BaudRate: br})
-		if err != nil {
-			if i < wait {
-				time.Sleep(10 * time.Millisecond)
-				continue
-			}
-			return err
-		}
-		break
-	}
-	defer p.Close()
-
-	tty, err := tty.Open()
-	if err != nil {
-		return err
-	}
-	defer tty.Close()
-
-	sig := make(chan os.Signal, 1)
-	signal.Notify(sig, os.Interrupt)
-	defer signal.Stop(sig)
-
-	go func() {
-		<-sig
-		tty.Close()
-		os.Exit(0)
-	}()
-
-	fmt.Printf("Connected to %s. Press Ctrl-C to exit.\n", port)
-
-	errCh := make(chan error, 1)
-
-	go func() {
-		buf := make([]byte, 100*1024)
-		for {
-			n, err := p.Read(buf)
-			if err != nil {
-				errCh <- fmt.Errorf("read error: %w", err)
-				return
-			}
-
-			if n == 0 {
-				continue
-			}
-			fmt.Printf("%v", string(buf[:n]))
-		}
-	}()
-
-	go func() {
-		for {
-			r, err := tty.ReadRune()
-			if err != nil {
-				errCh <- err
-				return
-			}
-			if r == 0 {
-				continue
-			}
-			p.Write([]byte(string(r)))
-		}
-	}()
-
-	return <-errCh
-}
@@ -1,5 +1,5 @@
-//go:build nrf || stm32 || (sam && atsamd51) || (sam && atsame5x)
-// +build nrf stm32 sam,atsamd51 sam,atsame5x
+//go:build stm32 || (sam && atsamd51) || (sam && atsame5x)
+// +build stm32 sam,atsamd51 sam,atsame5x

 package rand

@@ -0,0 +1,49 @@
+// Reads multiple rp2040 ADC channels concurrently. Including the internal temperature sensor
+
+package main
+
+import (
+	"fmt"
+	"machine"
+	"time"
+)
+
+type celsius float32
+
+func (c celsius) String() string {
+	return fmt.Sprintf("%4.1f℃", c)
+}
+
+// rp2040 ADC is 12 bits. Reading are shifted <<4 to fill the 16-bit range.
+var adcReading [3]uint16
+
+func readADC(a machine.ADC, w time.Duration, i int) {
+	for {
+		adcReading[i] = a.Get()
+		time.Sleep(w)
+	}
+}
+
+func main() {
+	machine.InitADC()
+	a0 := machine.ADC{machine.ADC0} // GPIO26 input
+	a1 := machine.ADC{machine.ADC1} // GPIO27 input
+	a2 := machine.ADC{machine.ADC2} // GPIO28 input
+	t := machine.ADC_TEMP_SENSOR    // Internal Temperature sensor
+	// Configure sets the GPIOs to PinAnalog mode
+	a0.Configure(machine.ADCConfig{})
+	a1.Configure(machine.ADCConfig{})
+	a2.Configure(machine.ADCConfig{})
+	// Configure powers on the temperature sensor
+	t.Configure(machine.ADCConfig{})
+
+	// Safe to read concurrently
+	go readADC(a0, 10*time.Millisecond, 0)
+	go readADC(a1, 17*time.Millisecond, 1)
+	go readADC(a2, 29*time.Millisecond, 2)
+
+	for {
+		fmt.Printf("ADC0: %5d ADC1: %5d ADC2: %5d Temp: %v\n\r", adcReading[0], adcReading[1], adcReading[2], celsius(float32(t.ReadTemperature())/1000))
+		time.Sleep(1000 * time.Millisecond)
+	}
+}
@@ -1,23 +0,0 @@
-// Read the internal temperature sensor of the chip.
-
-package main
-
-import (
-	"fmt"
-	"machine"
-	"time"
-)
-
-type celsius float32
-
-func (c celsius) String() string {
-	return fmt.Sprintf("%4.1f℃", c)
-}
-
-func main() {
-	for {
-		temp := celsius(float32(machine.ReadTemperature()) / 1000)
-		println("temperature:", temp.String())
-		time.Sleep(time.Second)
-	}
-}
@@ -21,14 +21,12 @@ $ tinygo build -o ./wasm.wasm -target wasm ./main/main.go
 This creates a `wasm.wasm` file, which we can load in JavaScript and execute in
 a browser.

-Next, choose which example you want to use:
-* [callback](callback): Defines and configures callbacks in Wasm.
-* [export](export): Defines callbacks in Wasm, but configures them in JavaScript.
-* [invoke](invoke): Invokes a function defined in JavaScript from Wasm.
-* [main](main): Prints a message to the JavaScript console from Wasm.
-* [slices](slices): Splits an Array defined in JavaScript from Wasm.
+This examples folder contains two examples that can be built using `make`:
+
+```bash
+$ make export
+```

-Let's say you chose [main](main), you'd build it like so:
 ```bash
 $ make main
 ```
@@ -44,8 +42,12 @@ Serving ./html on http://localhost:8080

 Use your web browser to visit http://localhost:8080.

-* Tip: Open the browser development tools (e.g. Right-click, Inspect in
-  FireFox) to see console output.
+* The wasm "export" example displays a simple math equation using HTML, with
+the result calculated dynamically using WebAssembly.  Changing any of the
+values on the left hand side triggers the exported wasm `update` function to
+recalculate the result.
+* The wasm "main" example uses `println` to write to your browser JavaScript
+console. You may need to open the browser development tools console to see it.

 ## How it works

@@ -8,12 +8,10 @@ import (
 var a, b int

 func main() {
-	wait := make(chan struct{}, 0)
 	document := js.Global().Get("document")
 	document.Call("getElementById", "a").Set("oninput", updater(&a))
 	document.Call("getElementById", "b").Set("oninput", updater(&b))
 	update()
-	<-wait
 }

 func updater(n *int) js.Func {
@@ -2,16 +2,12 @@

 .functype start_unwind (i32) -> ()
 .import_module start_unwind, asyncify
-.import_name start_unwind, start_unwind
 .functype stop_unwind () -> ()
 .import_module stop_unwind, asyncify
-.import_name stop_unwind, stop_unwind
 .functype start_rewind (i32) -> ()
 .import_module start_rewind, asyncify
-.import_name start_rewind, start_rewind
 .functype stop_rewind () -> ()
 .import_module stop_rewind, asyncify
-.import_name stop_rewind, stop_rewind

 .global  tinygo_unwind
 .hidden  tinygo_unwind
@@ -1,8 +1,5 @@
 // Windows on amd64 has a slightly different ABI than other (*nix) systems.
 // Therefore, assembly functions need to be tweaked slightly.
-//
-// The calling convention is described here:
-// https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170

 .section .text.tinygo_startTask,"ax"
 .global  tinygo_startTask
@@ -20,9 +17,8 @@ tinygo_startTask:
    // Branch to the "goroutine start" function.
    callq *%r12

-    // After return, exit this goroutine.
-    // This has to be a call, not a jump, to keep the stack correctly aligned.
-    callq tinygo_pause
+    // After return, exit this goroutine. This is a tail call.
+    jmp tinygo_pause

 .global tinygo_swapTask
 .section .text.tinygo_swapTask,"ax"
@@ -39,17 +35,6 @@ tinygo_swapTask:
    pushq %rsi
    pushq %rdi
    pushq %rbp
-    sub   $160, %rsp
-    movaps  %xmm6, 144(%rsp)
-    movaps  %xmm7, 128(%rsp)
-    movaps  %xmm8, 112(%rsp)
-    movaps  %xmm9,  96(%rsp)
-    movaps  %xmm10, 80(%rsp)
-    movaps  %xmm11, 64(%rsp)
-    movaps  %xmm12, 48(%rsp)
-    movaps  %xmm13, 32(%rsp)
-    movaps  %xmm14, 16(%rsp)
-    movaps  %xmm15,  0(%rsp)
    pushq %rbx

    // Save the current stack pointer in oldStack.
@@ -60,17 +45,6 @@ tinygo_swapTask:

    // Load saved register from the new stack.
    popq %rbx
-    movaps 0(%rsp),   %xmm15
-    movaps 16(%rsp),  %xmm14
-    movaps 32(%rsp),  %xmm13
-    movaps 48(%rsp),  %xmm12
-    movaps 64(%rsp),  %xmm11
-    movaps 80(%rsp),  %xmm10
-    movaps 96(%rsp),  %xmm9
-    movaps 112(%rsp), %xmm8
-    movaps 128(%rsp), %xmm7
-    movaps 144(%rsp), %xmm6
-    add   $160, %rsp
    popq %rbp
    popq %rdi
    popq %rsi
@@ -13,34 +13,15 @@ var systemStack uintptr
 // calleeSavedRegs is the list of registers that must be saved and restored when
 // switching between tasks. Also see task_stack_amd64_windows.S that relies on
 // the exact layout of this struct.
-// The calling convention is described here:
-// https://docs.microsoft.com/en-us/cpp/build/x64-calling-convention?view=msvc-170
-// Most importantly, these are the registers we need to save/restore:
-//
-// > The x64 ABI considers registers RBX, RBP, RDI, RSI, RSP, R12, R13, R14,
-// > R15, and XMM6-XMM15 nonvolatile. They must be saved and restored by a
-// > function that uses them.
 type calleeSavedRegs struct {
-	// Note: rbx is placed here so that the stack is correctly aligned when
-	// loading/storing the xmm registers.
-	rbx   uintptr
-	xmm15 [2]uint64
-	xmm14 [2]uint64
-	xmm13 [2]uint64
-	xmm12 [2]uint64
-	xmm11 [2]uint64
-	xmm10 [2]uint64
-	xmm9  [2]uint64
-	xmm8  [2]uint64
-	xmm7  [2]uint64
-	xmm6  [2]uint64
-	rbp   uintptr
-	rdi   uintptr
-	rsi   uintptr
-	r12   uintptr
-	r13   uintptr
-	r14   uintptr
-	r15   uintptr
+	rbx uintptr
+	rbp uintptr
+	rdi uintptr
+	rsi uintptr
+	r12 uintptr
+	r13 uintptr
+	r14 uintptr
+	r15 uintptr

 	pc uintptr
 }
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0x07738135
+const RESET_MAGIC_VALUE = 0x07738135

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0x07738135
+const RESET_MAGIC_VALUE = 0x07738135

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0x07738135
+const RESET_MAGIC_VALUE = 0x07738135

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0x07738135
+const RESET_MAGIC_VALUE = 0x07738135

 // GPIO Pins - Digital Low
 const (
@@ -12,9 +12,9 @@ const (

 const (
 	PB0 = portB + 0
-	PB1 = portB + 1 // peripherals: Timer1 channel A
-	PB2 = portB + 2 // peripherals: Timer1 channel B
-	PB3 = portB + 3 // peripherals: Timer2 channel A
+	PB1 = portB + 1
+	PB2 = portB + 2
+	PB3 = portB + 3
 	PB4 = portB + 4
 	PB5 = portB + 5
 	PB6 = portB + 6
@@ -30,9 +30,9 @@ const (
 	PD0 = portD + 0
 	PD1 = portD + 1
 	PD2 = portD + 2
-	PD3 = portD + 3 // peripherals: Timer2 channel B
+	PD3 = portD + 3
 	PD4 = portD + 4
-	PD5 = portD + 5 // peripherals: Timer0 channel B
-	PD6 = portD + 6 // peripherals: Timer0 channel A
+	PD5 = portD + 5
+	PD6 = portD + 6
 	PD7 = portD + 7
 )
@@ -10,38 +10,38 @@ func CPUFrequency() uint32 {

 // Hardware pins
 const (
-	PA00 Pin = 0 // peripherals: TCC2 channel 0
-	PA01 Pin = 1 // peripherals: TCC2 channel 1
+	PA00 Pin = 0
+	PA01 Pin = 1
 	PA02 Pin = 2
 	PA03 Pin = 3
-	PA04 Pin = 4  // peripherals: TCC0 channel 0
-	PA05 Pin = 5  // peripherals: TCC0 channel 1
-	PA06 Pin = 6  // peripherals: TCC1 channel 0
-	PA07 Pin = 7  // peripherals: TCC1 channel 1
-	PA08 Pin = 8  // peripherals: TCC0 channel 0, TCC1 channel 2
-	PA09 Pin = 9  // peripherals: TCC0 channel 1, TCC1 channel 3
-	PA10 Pin = 10 // peripherals: TCC1 channel 0, TCC0 channel 2
-	PA11 Pin = 11 // peripherals: TCC1 channel 1, TCC0 channel 3
-	PA12 Pin = 12 // peripherals: TCC2 channel 0, TCC0 channel 2
-	PA13 Pin = 13 // peripherals: TCC2 channel 1, TCC0 channel 3
-	PA14 Pin = 14 // peripherals: TCC0 channel 0
-	PA15 Pin = 15 // peripherals: TCC0 channel 1
-	PA16 Pin = 16 // peripherals: TCC2 channel 0, TCC0 channel 2
-	PA17 Pin = 17 // peripherals: TCC2 channel 1, TCC0 channel 3
-	PA18 Pin = 18 // peripherals: TCC0 channel 2
-	PA19 Pin = 19 // peripherals: TCC0 channel 3
-	PA20 Pin = 20 // peripherals: TCC0 channel 2
-	PA21 Pin = 21 // peripherals: TCC0 channel 3
-	PA22 Pin = 22 // peripherals: TCC0 channel 0
-	PA23 Pin = 23 // peripherals: TCC0 channel 1
-	PA24 Pin = 24 // peripherals: TCC1 channel 2
-	PA25 Pin = 25 // peripherals: TCC1 channel 3
+	PA04 Pin = 4
+	PA05 Pin = 5
+	PA06 Pin = 6
+	PA07 Pin = 7
+	PA08 Pin = 8
+	PA09 Pin = 9
+	PA10 Pin = 10
+	PA11 Pin = 11
+	PA12 Pin = 12
+	PA13 Pin = 13
+	PA14 Pin = 14
+	PA15 Pin = 15
+	PA16 Pin = 16
+	PA17 Pin = 17
+	PA18 Pin = 18
+	PA19 Pin = 19
+	PA20 Pin = 20
+	PA21 Pin = 21
+	PA22 Pin = 22
+	PA23 Pin = 23
+	PA24 Pin = 24
+	PA25 Pin = 25
 	PA26 Pin = 26
 	PA27 Pin = 27
 	PA28 Pin = 28
 	PA29 Pin = 29
-	PA30 Pin = 30 // peripherals: TCC1 channel 0
-	PA31 Pin = 31 // peripherals: TCC1 channel 1
+	PA30 Pin = 30
+	PA31 Pin = 31
 	PB00 Pin = 32
 	PB01 Pin = 33
 	PB02 Pin = 34
@@ -52,14 +52,14 @@ const (
 	PB07 Pin = 39
 	PB08 Pin = 40
 	PB09 Pin = 41
-	PB10 Pin = 42 // peripherals: TCC0 channel 0
-	PB11 Pin = 43 // peripherals: TCC0 channel 1
-	PB12 Pin = 44 // peripherals: TCC0 channel 2
-	PB13 Pin = 45 // peripherals: TCC0 channel 3
+	PB10 Pin = 42
+	PB11 Pin = 43
+	PB12 Pin = 44
+	PB13 Pin = 45
 	PB14 Pin = 46
 	PB15 Pin = 47
-	PB16 Pin = 48 // peripherals: TCC0 channel 0
-	PB17 Pin = 49 // peripherals: TCC0 channel 1
+	PB16 Pin = 48
+	PB17 Pin = 49
 	PB18 Pin = 50
 	PB19 Pin = 51
 	PB20 Pin = 52
@@ -72,6 +72,6 @@ const (
 	PB27 Pin = 59
 	PB28 Pin = 60
 	PB29 Pin = 61
-	PB30 Pin = 62 // peripherals: TCC0 channel 0, TCC1 channel 2
-	PB31 Pin = 63 // peripherals: TCC0 channel 1, TCC1 channel 3
+	PB30 Pin = 62
+	PB31 Pin = 63
 )
@@ -8,7 +8,7 @@ import (
 )

 // Definition for compatibility, but not used
-const resetMagicValue = 0x00000000
+const RESET_MAGIC_VALUE = 0x00000000

 const (
 	LED    = PC18
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -8,7 +8,7 @@ import (
 )

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -245,7 +245,7 @@ const (

 // Other peripheral constants
 const (
-	resetMagicValue = 0xF01669EF // Used to reset into bootloader
+	RESET_MAGIC_VALUE = 0xF01669EF // Used to reset into bootloader
 )

 // USB CDC pins
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xF01669EF
+const RESET_MAGIC_VALUE = 0xF01669EF

 // Digital pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -7,7 +7,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0x07738135
+const RESET_MAGIC_VALUE = 0x07738135

 // Note: On the P1AM-100, pins D8, D9, D10, A3, and A4 are used for
 // communication with the base controller.
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -36,9 +36,10 @@ const (
 )

 const (
-	NEOPIXEL       = GPIO12
-	WS2812         = GPIO12
-	NEOPIXEL_POWER = GPIO11
+	NEOPIXELS       = GPIO12
+	WS2812          = GPIO12
+	NEOPIXELS_POWER = GPIO11
+	LED             = GPIO20
 )

 // I2C Pins.
@@ -115,5 +116,5 @@ const (

 var (
 	usb_VID uint16 = 0x239A
-	usb_PID uint16 = 0x80F7
+	usb_PID uint16 = 0x80F1
 )
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 const (
 	ADC0 = A0
@@ -104,7 +104,7 @@ const (

 var (
 	usb_VID uint16 = 0x2886
-	usb_PID uint16 = 0x8045
+	usb_PID uint16 = 0x0045
 )

 var (
@@ -4,7 +4,7 @@
 package machine

 // used to reset into bootloader
-const resetMagicValue = 0xf01669ef
+const RESET_MAGIC_VALUE = 0xf01669ef

 // GPIO Pins
 const (
@@ -8,8 +8,6 @@ import (
 )

 // TWI_FREQ is the I2C bus speed. Normally either 100 kHz, or 400 kHz for high-speed bus.
-//
-// Deprecated: use 100 * machine.KHz or 400 * machine.KHz instead.
 const (
 	TWI_FREQ_100KHZ = 100000
 	TWI_FREQ_400KHZ = 400000
@@ -18,13 +18,6 @@ var (
 // particular chip but instead runs in WebAssembly for example.
 const Device = deviceName

-// Generic constants.
-const (
-	KHz = 1000
-	MHz = 1000_000
-	GHz = 1000_000_000
-)
-
 // PinMode sets the direction and pull mode of the pin. For example, PinOutput
 // sets the pin as an output and PinInputPullup sets the pin as an input with a
 // pull-up.
@@ -26,7 +26,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}

 	// Activate internal pullups for twi.
@@ -38,10 +38,10 @@ const (
 	PB1 = portB + 1
 	PB2 = portB + 2
 	PB3 = portB + 3
-	PB4 = portB + 4 // peripherals: Timer2 channel A
-	PB5 = portB + 5 // peripherals: Timer1 channel A
-	PB6 = portB + 6 // peripherals: Timer1 channel B
-	PB7 = portB + 7 // peripherals: Timer0 channel A
+	PB4 = portB + 4
+	PB5 = portB + 5
+	PB6 = portB + 6
+	PB7 = portB + 7
 	PC0 = portC + 0
 	PC1 = portC + 1
 	PC2 = portC + 2
@@ -57,9 +57,9 @@ const (
 	PD7 = portD + 7
 	PE0 = portE + 0
 	PE1 = portE + 1
-	PE3 = portE + 3 // peripherals: Timer3 channel A
-	PE4 = portE + 4 // peripherals: Timer3 channel B
-	PE5 = portE + 5 // peripherals: Timer3 channel C
+	PE3 = portE + 3
+	PE4 = portE + 4
+	PE5 = portE + 5
 	PE6 = portE + 6
 	PF0 = portF + 0
 	PF1 = portF + 1
@@ -72,13 +72,13 @@ const (
 	PG0 = portG + 0
 	PG1 = portG + 1
 	PG2 = portG + 2
-	PG5 = portG + 5 // peripherals: Timer0 channel B
+	PG5 = portG + 5
 	PH0 = portH + 0
 	PH1 = portH + 1
-	PH3 = portH + 3 // peripherals: Timer4 channel A
-	PH4 = portH + 4 // peripherals: Timer4 channel B
-	PH5 = portH + 5 // peripherals: Timer4 channel C
-	PH6 = portH + 6 // peripherals: Timer0 channel B
+	PH3 = portH + 3
+	PH4 = portH + 4
+	PH5 = portH + 5
+	PH6 = portH + 6
 	PJ0 = portJ + 0
 	PJ1 = portJ + 1
 	PK0 = portK + 0
@@ -92,9 +92,9 @@ const (
 	PL0 = portL + 0
 	PL1 = portL + 1
 	PL2 = portL + 2
-	PL3 = portL + 3 // peripherals: Timer5 channel A
-	PL4 = portL + 4 // peripherals: Timer5 channel B
-	PL5 = portL + 5 // peripherals: Timer5 channel C
+	PL3 = portL + 3
+	PL4 = portL + 4
+	PL5 = portL + 5
 	PL6 = portL + 6
 	PL7 = portL + 7
 )
@@ -10,6 +10,7 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
+	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -17,20 +18,20 @@ import (
 const deviceName = sam.Device

 const (
+	PinAnalog    PinMode = 1
+	PinSERCOM    PinMode = 2
+	PinSERCOMAlt PinMode = 3
+	PinTimer     PinMode = 4
+	PinTimerAlt  PinMode = 5
+	PinCom       PinMode = 6
+	//PinAC_CLK        PinMode = 7
+	PinDigital       PinMode = 8
 	PinInput         PinMode = 9
 	PinInputPullup   PinMode = 10
 	PinOutput        PinMode = 11
+	PinTCC           PinMode = PinTimer
+	PinTCCAlt        PinMode = PinTimerAlt
 	PinInputPulldown PinMode = 12
-
-	// internal pin modes
-	pinAnalog    PinMode = 1
-	pinSERCOM    PinMode = 2
-	pinSERCOMAlt PinMode = 3
-	pinTCC       PinMode = 4
-	pinTCCAlt    PinMode = 5
-	pinCom       PinMode = 6
-	//PinAC_CLK        PinMode = 7
-	pinDigital PinMode = 8
 )

 type PinChange uint8
@@ -149,7 +150,7 @@ func findPinPadMapping(sercom uint8, pin Pin) (pinMode PinMode, pad uint32, ok b
 	if upper != 0 {
 		// SERCOM
 		if (upper>>1)-1 == sercom {
-			pinMode = pinSERCOM
+			pinMode = PinSERCOM
 			pad |= uint32((upper & 1) << 1)
 			ok = true
 		}
@@ -157,7 +158,7 @@ func findPinPadMapping(sercom uint8, pin Pin) (pinMode PinMode, pad uint32, ok b
 	if lower != 0 {
 		// SERCOM-ALT
 		if (lower>>1)-1 == sercom {
-			pinMode = pinSERCOMAlt
+			pinMode = PinSERCOMAlt
 			pad |= uint32((lower & 1) << 1)
 			ok = true
 		}
@@ -381,7 +382,7 @@ func (a ADC) Configure(config ADCConfig) {
 	// 1/2 VDDANA = 0.5 * 3V3 = 1.65V
 	sam.ADC.REFCTRL.SetBits(sam.ADC_REFCTRL_REFSEL_INTVCC1 << sam.ADC_REFCTRL_REFSEL_Pos)

-	a.Pin.Configure(PinConfig{Mode: pinAnalog})
+	a.Pin.Configure(PinConfig{Mode: PinAnalog})
 	return
 }

@@ -676,7 +677,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}
 	if config.SDA == 0 && config.SCL == 0 {
 		config.SDA = SDA_PIN
@@ -1000,11 +1001,11 @@ func (i2s I2S) Configure(config I2SConfig) {
 	}

 	// configure pin for clock
-	config.SCK.Configure(PinConfig{Mode: pinCom})
+	config.SCK.Configure(PinConfig{Mode: PinCom})

 	// configure pin for WS, if needed
 	if config.WS != NoPin {
-		config.WS.Configure(PinConfig{Mode: pinCom})
+		config.WS.Configure(PinConfig{Mode: PinCom})
 	}

 	// now set serializer data size.
@@ -1043,7 +1044,7 @@ func (i2s I2S) Configure(config I2SConfig) {
 	}

 	// configure data pin
-	config.SD.Configure(PinConfig{Mode: pinCom})
+	config.SD.Configure(PinConfig{Mode: PinCom})

 	// re-enable
 	i2s.Bus.CTRLA.SetBits(sam.I2S_CTRLA_ENABLE)
@@ -1273,6 +1274,10 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 	return byte(spi.Bus.DATA.Get()), nil
 }

+var (
+	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
+)
+
 // Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
 // interface, there must always be the same number of bytes written as bytes read.
 // The Tx method knows about this, and offers a few different ways of calling it.
@@ -1636,12 +1641,12 @@ func findPinTimerMapping(timer uint8, pin Pin) (PinMode, uint8) {
 	if mapping&0x07 == timer+1 {
 		// PWM output is on peripheral function E.
 		evenChannel := ((mapping >> 3) & 1) * 2
-		return pinTCC, evenChannel + uint8(pin&1)
+		return PinTCC, evenChannel + uint8(pin&1)
 	}
 	if (mapping&0x70)>>4 == timer+1 {
 		// PWM output is on peripheral function F.
 		evenChannel := ((mapping >> 7) & 1) * 2
-		return pinTCCAlt, evenChannel + uint8(pin&1)
+		return PinTCCAlt, evenChannel + uint8(pin&1)
 	}
 	return 0, 0
 }
@@ -1735,7 +1740,7 @@ func EnterBootloader() {

 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = resetMagicValue
+	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = RESET_MAGIC_VALUE

 	arm.SystemReset()
 }
@@ -37,8 +37,8 @@ func (dev *USBDevice) Configure(config UARTConfig) {
 	sam.USB_DEVICE.DESCADD.Set(uint32(uintptr(unsafe.Pointer(&usbEndpointDescriptors))))

 	// configure pins
-	USBCDC_DM_PIN.Configure(PinConfig{Mode: pinCom})
-	USBCDC_DP_PIN.Configure(PinConfig{Mode: pinCom})
+	USBCDC_DM_PIN.Configure(PinConfig{Mode: PinCom})
+	USBCDC_DP_PIN.Configure(PinConfig{Mode: PinCom})

 	// performs pad calibration from store fuses
 	handlePadCalibration()
@@ -86,53 +86,53 @@ func (p Pin) Configure(config PinConfig) {
 		sam.PORT.OUTSET0.Set(1 << uint8(p))
 		p.setPinCfg(sam.PORT_PINCFG0_INEN | sam.PORT_PINCFG0_PULLEN)

-	case pinSERCOM:
+	case PinSERCOM:
 		if uint8(p)&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR | sam.PORT_PINCFG0_INEN)

-	case pinSERCOMAlt:
+	case PinSERCOMAlt:
 		if uint8(p)&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)

-	case pinCom:
+	case PinCom:
 		if uint8(p)&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN)
-	case pinAnalog:
+	case PinAnalog:
 		if uint8(p)&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)
@@ -137,53 +137,53 @@ func (p Pin) Configure(config PinConfig) {
 			p.setPinCfg(sam.PORT_PINCFG0_INEN | sam.PORT_PINCFG0_PULLEN)
 		}

-	case pinSERCOM:
+	case PinSERCOM:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR | sam.PORT_PINCFG0_INEN)

-	case pinSERCOMAlt:
+	case PinSERCOMAlt:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)

-	case pinCom:
+	case PinCom:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN)
-	case pinAnalog:
+	case PinAnalog:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_PMUX0_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_PMUX0_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_PMUX0_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_PMUX0_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)
@@ -10,6 +10,7 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
+	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -21,29 +22,30 @@ func CPUFrequency() uint32 {
 }

 const (
+	PinAnalog        PinMode = 1
+	PinSERCOM        PinMode = 2
+	PinSERCOMAlt     PinMode = 3
+	PinTimer         PinMode = 4
+	PinTimerAlt      PinMode = 5
+	PinTCCPDEC       PinMode = 6
+	PinCom           PinMode = 7
+	PinSDHC          PinMode = 8
+	PinI2S           PinMode = 9
+	PinPCC           PinMode = 10
+	PinGMAC          PinMode = 11
+	PinACCLK         PinMode = 12
+	PinCCL           PinMode = 13
+	PinDigital       PinMode = 14
 	PinInput         PinMode = 15
 	PinInputPullup   PinMode = 16
 	PinOutput        PinMode = 17
+	PinTCCE          PinMode = PinTimer
+	PinTCCF          PinMode = PinTimerAlt
+	PinTCCG          PinMode = PinTCCPDEC
 	PinInputPulldown PinMode = 18
-
-	// internal pin modes
-	pinAnalog    PinMode = 1
-	pinSERCOM    PinMode = 2
-	pinSERCOMAlt PinMode = 3
-	pinTCCE      PinMode = 4
-	pinTCCF      PinMode = 5
-	pinTCCG      PinMode = 6
-	pinCom       PinMode = 7
-	pinSDHC      PinMode = 8
-	pinI2S       PinMode = 9
-	pinPCC       PinMode = 10
-	pinGMAC      PinMode = 11
-	pinACCLK     PinMode = 12
-	pinCCL       PinMode = 13
-	pinDigital   PinMode = 14
-	pinCAN       PinMode = 19
-	pinCAN0      PinMode = pinSDHC
-	pinCAN1      PinMode = pinCom
+	PinCAN           PinMode = 19
+	PinCAN0          PinMode = PinSDHC
+	PinCAN1          PinMode = PinCom
 )

 type PinChange uint8
@@ -76,86 +78,86 @@ const (
 	PA05 Pin = 5
 	PA06 Pin = 6
 	PA07 Pin = 7
-	PA08 Pin = 8  // peripherals: TCC0 channel 0, TCC1 channel 4
-	PA09 Pin = 9  // peripherals: TCC0 channel 1, TCC1 channel 5
-	PA10 Pin = 10 // peripherals: TCC0 channel 2, TCC1 channel 6
-	PA11 Pin = 11 // peripherals: TCC0 channel 3, TCC1 channel 7
-	PA12 Pin = 12 // peripherals: TCC0 channel 6, TCC1 channel 2
-	PA13 Pin = 13 // peripherals: TCC0 channel 7, TCC1 channel 3
-	PA14 Pin = 14 // peripherals: TCC2 channel 0, TCC1 channel 2
-	PA15 Pin = 15 // peripherals: TCC2 channel 1, TCC1 channel 3
-	PA16 Pin = 16 // peripherals: TCC1 channel 0, TCC0 channel 4
-	PA17 Pin = 17 // peripherals: TCC1 channel 1, TCC0 channel 5
-	PA18 Pin = 18 // peripherals: TCC1 channel 2, TCC0 channel 6
-	PA19 Pin = 19 // peripherals: TCC1 channel 3, TCC0 channel 7
-	PA20 Pin = 20 // peripherals: TCC1 channel 4, TCC0 channel 0
-	PA21 Pin = 21 // peripherals: TCC1 channel 5, TCC0 channel 1
-	PA22 Pin = 22 // peripherals: TCC1 channel 6, TCC0 channel 2
-	PA23 Pin = 23 // peripherals: TCC1 channel 7, TCC0 channel 3
-	PA24 Pin = 24 // peripherals: TCC2 channel 2
-	PA25 Pin = 25 // peripherals: TCC2 channel 3
+	PA08 Pin = 8
+	PA09 Pin = 9
+	PA10 Pin = 10
+	PA11 Pin = 11
+	PA12 Pin = 12
+	PA13 Pin = 13
+	PA14 Pin = 14
+	PA15 Pin = 15
+	PA16 Pin = 16
+	PA17 Pin = 17
+	PA18 Pin = 18
+	PA19 Pin = 19
+	PA20 Pin = 20
+	PA21 Pin = 21
+	PA22 Pin = 22
+	PA23 Pin = 23
+	PA24 Pin = 24
+	PA25 Pin = 25
 	PA26 Pin = 26
 	PA27 Pin = 27
 	PA28 Pin = 28
 	PA29 Pin = 29
-	PA30 Pin = 30 // peripherals: TCC2 channel 0
-	PA31 Pin = 31 // peripherals: TCC2 channel 1
+	PA30 Pin = 30
+	PA31 Pin = 31
 	PB00 Pin = 32
 	PB01 Pin = 33
-	PB02 Pin = 34 // peripherals: TCC2 channel 2
-	PB03 Pin = 35 // peripherals: TCC2 channel 3
+	PB02 Pin = 34
+	PB03 Pin = 35
 	PB04 Pin = 36
 	PB05 Pin = 37
 	PB06 Pin = 38
 	PB07 Pin = 39
 	PB08 Pin = 40
 	PB09 Pin = 41
-	PB10 Pin = 42 // peripherals: TCC0 channel 4, TCC1 channel 0
-	PB11 Pin = 43 // peripherals: TCC0 channel 5, TCC1 channel 1
-	PB12 Pin = 44 // peripherals: TCC3 channel 0, TCC0 channel 0
-	PB13 Pin = 45 // peripherals: TCC3 channel 1, TCC0 channel 1
-	PB14 Pin = 46 // peripherals: TCC4 channel 0, TCC0 channel 2
-	PB15 Pin = 47 // peripherals: TCC4 channel 1, TCC0 channel 3
-	PB16 Pin = 48 // peripherals: TCC3 channel 0, TCC0 channel 4
-	PB17 Pin = 49 // peripherals: TCC3 channel 1, TCC0 channel 5
-	PB18 Pin = 50 // peripherals: TCC1 channel 0
-	PB19 Pin = 51 // peripherals: TCC1 channel 1
-	PB20 Pin = 52 // peripherals: TCC1 channel 2
-	PB21 Pin = 53 // peripherals: TCC1 channel 3
+	PB10 Pin = 42
+	PB11 Pin = 43
+	PB12 Pin = 44
+	PB13 Pin = 45
+	PB14 Pin = 46
+	PB15 Pin = 47
+	PB16 Pin = 48
+	PB17 Pin = 49
+	PB18 Pin = 50
+	PB19 Pin = 51
+	PB20 Pin = 52
+	PB21 Pin = 53
 	PB22 Pin = 54
 	PB23 Pin = 55
 	PB24 Pin = 56
 	PB25 Pin = 57
-	PB26 Pin = 58 // peripherals: TCC1 channel 2
-	PB27 Pin = 59 // peripherals: TCC1 channel 3
-	PB28 Pin = 60 // peripherals: TCC1 channel 4
-	PB29 Pin = 61 // peripherals: TCC1 channel 5
-	PB30 Pin = 62 // peripherals: TCC4 channel 0, TCC0 channel 6
-	PB31 Pin = 63 // peripherals: TCC4 channel 1, TCC0 channel 7
+	PB26 Pin = 58
+	PB27 Pin = 59
+	PB28 Pin = 60
+	PB29 Pin = 61
+	PB30 Pin = 62
+	PB31 Pin = 63
 	PC00 Pin = 64
 	PC01 Pin = 65
 	PC02 Pin = 66
 	PC03 Pin = 67
-	PC04 Pin = 68 // peripherals: TCC0 channel 0
-	PC05 Pin = 69 // peripherals: TCC0 channel 1
+	PC04 Pin = 68
+	PC05 Pin = 69
 	PC06 Pin = 70
 	PC07 Pin = 71
 	PC08 Pin = 72
 	PC09 Pin = 73
-	PC10 Pin = 74 // peripherals: TCC0 channel 0, TCC1 channel 4
-	PC11 Pin = 75 // peripherals: TCC0 channel 1, TCC1 channel 5
-	PC12 Pin = 76 // peripherals: TCC0 channel 2, TCC1 channel 6
-	PC13 Pin = 77 // peripherals: TCC0 channel 3, TCC1 channel 7
-	PC14 Pin = 78 // peripherals: TCC0 channel 4, TCC1 channel 0
-	PC15 Pin = 79 // peripherals: TCC0 channel 5, TCC1 channel 1
-	PC16 Pin = 80 // peripherals: TCC0 channel 0
-	PC17 Pin = 81 // peripherals: TCC0 channel 1
-	PC18 Pin = 82 // peripherals: TCC0 channel 2
-	PC19 Pin = 83 // peripherals: TCC0 channel 3
-	PC20 Pin = 84 // peripherals: TCC0 channel 4
-	PC21 Pin = 85 // peripherals: TCC0 channel 5
-	PC22 Pin = 86 // peripherals: TCC0 channel 6
-	PC23 Pin = 87 // peripherals: TCC0 channel 7
+	PC10 Pin = 74
+	PC11 Pin = 75
+	PC12 Pin = 76
+	PC13 Pin = 77
+	PC14 Pin = 78
+	PC15 Pin = 79
+	PC16 Pin = 80
+	PC17 Pin = 81
+	PC18 Pin = 82
+	PC19 Pin = 83
+	PC20 Pin = 84
+	PC21 Pin = 85
+	PC22 Pin = 86
+	PC23 Pin = 87
 	PC24 Pin = 88
 	PC25 Pin = 89
 	PC26 Pin = 90
@@ -172,20 +174,20 @@ const (
 	PD05 Pin = 101
 	PD06 Pin = 102
 	PD07 Pin = 103
-	PD08 Pin = 104 // peripherals: TCC0 channel 1
-	PD09 Pin = 105 // peripherals: TCC0 channel 2
-	PD10 Pin = 106 // peripherals: TCC0 channel 3
-	PD11 Pin = 107 // peripherals: TCC0 channel 4
-	PD12 Pin = 108 // peripherals: TCC0 channel 5
-	PD13 Pin = 109 // peripherals: TCC0 channel 6
+	PD08 Pin = 104
+	PD09 Pin = 105
+	PD10 Pin = 106
+	PD11 Pin = 107
+	PD12 Pin = 108
+	PD13 Pin = 109
 	PD14 Pin = 110
 	PD15 Pin = 111
 	PD16 Pin = 112
 	PD17 Pin = 113
 	PD18 Pin = 114
 	PD19 Pin = 115
-	PD20 Pin = 116 // peripherals: TCC1 channel 0
-	PD21 Pin = 117 // peripherals: TCC1 channel 1
+	PD20 Pin = 116
+	PD21 Pin = 117
 	PD22 Pin = 118
 	PD23 Pin = 119
 	PD24 Pin = 120
@@ -337,7 +339,7 @@ func findPinPadMapping(sercom uint8, pin Pin) (pinMode PinMode, pad uint32, ok b
 	if upper != 0 {
 		// SERCOM
 		if (upper>>4)-1 == sercom {
-			pinMode = pinSERCOM
+			pinMode = PinSERCOM
 			pad |= uint32(upper % 4)
 			ok = true
 		}
@@ -345,7 +347,7 @@ func findPinPadMapping(sercom uint8, pin Pin) (pinMode PinMode, pad uint32, ok b
 	if lower != 0 {
 		// SERCOM-ALT
 		if (lower>>4)-1 == sercom {
-			pinMode = pinSERCOMAlt
+			pinMode = PinSERCOMAlt
 			pad |= uint32(lower % 4)
 			ok = true
 		}
@@ -579,65 +581,65 @@ func (p Pin) Configure(config PinConfig) {
 		sam.PORT.GROUP[group].OUTSET.Set(1 << pin_in_group)
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_INEN | sam.PORT_GROUP_PINCFG_PULLEN)

-	case pinSERCOM:
+	case PinSERCOM:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOM) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOM) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_PMUXEN | sam.PORT_GROUP_PINCFG_DRVSTR | sam.PORT_GROUP_PINCFG_INEN)

-	case pinSERCOMAlt:
+	case PinSERCOMAlt:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSERCOMAlt) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSERCOMAlt) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_PMUXEN | sam.PORT_GROUP_PINCFG_DRVSTR)

-	case pinCom:
+	case PinCom:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXE_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXO_Msk
-			p.setPMux(val | (uint8(pinCom) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinCom) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_PMUXEN)
-	case pinAnalog:
+	case PinAnalog:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXE_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXO_Msk
-			p.setPMux(val | (uint8(pinAnalog) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinAnalog) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_PMUXEN | sam.PORT_GROUP_PINCFG_DRVSTR)
-	case pinSDHC:
+	case PinSDHC:
 		if p&1 > 0 {
 			// odd pin, so save the even pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXE_Msk
-			p.setPMux(val | (uint8(pinSDHC) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
+			p.setPMux(val | (uint8(PinSDHC) << sam.PORT_GROUP_PMUX_PMUXO_Pos))
 		} else {
 			// even pin, so save the odd pins
 			val := p.getPMux() & sam.PORT_GROUP_PMUX_PMUXO_Msk
-			p.setPMux(val | (uint8(pinSDHC) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
+			p.setPMux(val | (uint8(PinSDHC) << sam.PORT_GROUP_PMUX_PMUXE_Pos))
 		}
 		// enable port config
 		p.setPinCfg(sam.PORT_GROUP_PINCFG_PMUXEN)
@@ -813,7 +815,7 @@ func (a ADC) Configure(config ADCConfig) {
 		adc.REFCTRL.SetBits(sam.ADC_REFCTRL_REFSEL_INTVCC1)
 	}

-	a.Pin.Configure(PinConfig{Mode: pinAnalog})
+	a.Pin.Configure(PinConfig{Mode: PinAnalog})
 }

 // Get returns the current value of a ADC pin, in the range 0..0xffff.
@@ -1149,7 +1151,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}

 	// Use default I2C pins if not set.
@@ -1525,6 +1527,10 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 	return byte(spi.Bus.DATA.Get()), nil
 }

+var (
+	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
+)
+
 // Tx handles read/write operation for SPI interface. Since SPI is a syncronous write/read
 // interface, there must always be the same number of bytes written as bytes read.
 // The Tx method knows about this, and offers a few different ways of calling it.
@@ -1866,7 +1872,7 @@ var pinTimerMapping = [...]struct{ F, G uint8 }{
 	PB02 / 2: {pinTCC2_2, 0},
 }

-// findPinPadMapping returns the pin mode (pinTCCF or pinTCCG) and the channel
+// findPinPadMapping returns the pin mode (PinTCCF or PinTCCG) and the channel
 // number for a given timer and pin. A zero PinMode is returned if no mapping
 // could be found.
 func findPinTimerMapping(timer uint8, pin Pin) (PinMode, uint8) {
@@ -1878,12 +1884,12 @@ func findPinTimerMapping(timer uint8, pin Pin) (PinMode, uint8) {

 	// Check for column F in the datasheet.
 	if mapping.F>>4-1 == timer {
-		return pinTCCF, mapping.F&0x0f + uint8(pin)&1
+		return PinTCCF, mapping.F&0x0f + uint8(pin)&1
 	}

 	// Check for column G in the datasheet.
 	if mapping.G>>4-1 == timer {
-		return pinTCCG, mapping.G&0x0f + uint8(pin)&1
+		return PinTCCG, mapping.G&0x0f + uint8(pin)&1
 	}

 	// Nothing found.
@@ -1974,7 +1980,7 @@ func EnterBootloader() {

 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = resetMagicValue
+	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = RESET_MAGIC_VALUE

 	arm.SystemReset()
 }
@@ -37,8 +37,8 @@ func (dev *USBDevice) Configure(config UARTConfig) {
 	sam.USB_DEVICE.DESCADD.Set(uint32(uintptr(unsafe.Pointer(&usbEndpointDescriptors))))

 	// configure pins
-	USBCDC_DM_PIN.Configure(PinConfig{Mode: pinCom})
-	USBCDC_DP_PIN.Configure(PinConfig{Mode: pinCom})
+	USBCDC_DM_PIN.Configure(PinConfig{Mode: PinCom})
+	USBCDC_DP_PIN.Configure(PinConfig{Mode: PinCom})

 	// performs pad calibration from store fuses
 	handlePadCalibration()
@@ -68,9 +68,9 @@ func (can *CAN) Configure(config CANConfig) error {
 		config.Standby.Low()
 	}

-	mode := pinCAN0
+	mode := PinCAN0
 	if can.instance() == 1 {
-		mode = pinCAN1
+		mode = PinCAN1
 	}

 	config.Rx.Configure(PinConfig{Mode: mode})
@@ -59,9 +59,12 @@ type PinChange uint8

 // Pin change interrupt constants for SetInterrupt.
 const (
-	PinRising PinChange = iota + 1
+	PinNoInterrupt PinChange = iota
+	PinRising
 	PinFalling
 	PinToggle
+	PinLowLevel
+	PinHighLevel
 )

 // Configure this pin with the given configuration.
@@ -187,7 +190,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {
 		return ErrInvalidInputPin
 	}

-	if callback == nil {
+	if callback == nil || change == PinNoInterrupt {
 		// Disable this pin interrupt
 		p.pin().ClearBits(esp.GPIO_PIN_PIN_INT_TYPE_Msk | esp.GPIO_PIN_PIN_INT_ENA_Msk)

@@ -261,6 +264,15 @@ type UART struct {
 	DataOverflowDetected bool // set when data overflow detected in UART FIFO buffer or RingBuffer
 }

+type UARTStopBits int
+
+const (
+	UARTStopBits_Default UARTStopBits = iota
+	UARTStopBits_1
+	UARTStopBits_1_5
+	UARTStopBits_2
+)
+
 const (
 	defaultDataBits = 8
 	defaultStopBit  = 1
@@ -18,11 +18,9 @@ func CPUFrequency() uint32 {
 const (
 	PinInput PinMode = iota
 	PinOutput
-
-	// internal pin modes
-	pinPWM
-	pinSPI
-	pinI2C = pinSPI
+	PinPWM
+	PinSPI
+	PinI2C = PinSPI
 )

 // Configure this pin with the given configuration.
@@ -31,10 +29,10 @@ func (p Pin) Configure(config PinConfig) {
 	switch config.Mode {
 	case PinOutput:
 		sifive.GPIO0.OUTPUT_EN.SetBits(1 << uint8(p))
-	case pinPWM:
+	case PinPWM:
 		sifive.GPIO0.IOF_EN.SetBits(1 << uint8(p))
 		sifive.GPIO0.IOF_SEL.SetBits(1 << uint8(p))
-	case pinSPI:
+	case PinSPI:
 		sifive.GPIO0.IOF_EN.SetBits(1 << uint8(p))
 		sifive.GPIO0.IOF_SEL.ClearBits(1 << uint8(p))
 	}
@@ -147,9 +145,9 @@ func (spi SPI) Configure(config SPIConfig) error {
 	}

 	// enable pins for SPI
-	config.SCK.Configure(PinConfig{Mode: pinSPI})
-	config.SDO.Configure(PinConfig{Mode: pinSPI})
-	config.SDI.Configure(PinConfig{Mode: pinSPI})
+	config.SCK.Configure(PinConfig{Mode: PinSPI})
+	config.SDO.Configure(PinConfig{Mode: PinSPI})
+	config.SDI.Configure(PinConfig{Mode: PinSPI})

 	// set default frequency
 	if config.Frequency == 0 {
@@ -233,7 +231,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 	var i2cClockFrequency uint32 = 32000000
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}

 	if config.SDA == 0 && config.SCL == 0 {
@@ -253,8 +251,8 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 	// enable controller
 	i2c.Bus.CTR.SetBits(sifive.I2C_CTR_EN)

-	config.SDA.Configure(PinConfig{Mode: pinI2C})
-	config.SCL.Configure(PinConfig{Mode: pinI2C})
+	config.SDA.Configure(PinConfig{Mode: PinI2C})
+	config.SCL.Configure(PinConfig{Mode: PinI2C})

 	return nil
 }
@@ -23,17 +23,11 @@ type PinChange uint8
 // Pin modes.
 const (
 	PinInput PinMode = iota
-	PinInputPullup
-	PinInputPulldown
+	PinInputPullUp
+	PinInputPullDown
 	PinOutput
 )

-// Deprecated: use PinInputPullup and PinInputPulldown instead.
-const (
-	PinInputPullUp   = PinInputPullup
-	PinInputPullDown = PinInputPulldown
-)
-
 // FPIOA internal pull resistors.
 const (
 	fpioaPullNone fpioaPullMode = iota
@@ -95,10 +89,10 @@ func (p Pin) Configure(config PinConfig) {
 	case PinInput:
 		p.setFPIOAIOPull(fpioaPullNone)
 		input = true
-	case PinInputPullup:
+	case PinInputPullUp:
 		p.setFPIOAIOPull(fpioaPullUp)
 		input = true
-	case PinInputPulldown:
+	case PinInputPullDown:
 		p.setFPIOAIOPull(fpioaPullDown)
 		input = true
 	case PinOutput:
@@ -523,7 +517,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {

 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}

 	if config.SDA == 0 && config.SCL == 0 {
@@ -21,40 +21,36 @@ func CPUFrequency() uint32 {
 const (
 	// GPIO
 	PinInput PinMode = iota
-	PinInputPullup
-	PinInputPulldown
+	PinInputPullUp
+	PinInputPullDown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable

 	// ADC
-	pinInputAnalog
+	PinInputAnalog

 	// UART
-	pinModeUARTTX
-	pinModeUARTRX
+	PinModeUARTTX
+	PinModeUARTRX

 	// SPI
-	pinModeSPISDI
-	pinModeSPISDO
-	pinModeSPICLK
-	pinModeSPICS
+	PinModeSPISDI
+	PinModeSPISDO
+	PinModeSPICLK
+	PinModeSPICS

 	// I2C
-	pinModeI2CSDA
-	pinModeI2CSCL
-)
-
-// Deprecated: use PinInputPullup and PinInputPulldown instead.
-const (
-	PinInputPullUp   = PinInputPullup
-	PinInputPullDown = PinInputPulldown
+	PinModeI2CSDA
+	PinModeI2CSCL
 )

 type PinChange uint8

 const (
-	PinRising PinChange = iota + 2
+	PinLow PinChange = iota
+	PinHigh
+	PinRising
 	PinFalling
 	PinToggle
 )
@@ -263,11 +259,11 @@ func (p Pin) Configure(config PinConfig) {
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7))

-	case PinInputPullup:
+	case PinInputPullUp:
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7) | pke | pue | pup(3) | hys)

-	case PinInputPulldown:
+	case PinInputPullDown:
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7) | pke | pue | hys)

@@ -283,29 +279,29 @@ func (p Pin) Configure(config PinConfig) {
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7) | hys)

-	case pinInputAnalog:
+	case PinInputAnalog:
 		gpio.GDIR.ClearBits(p.getMask())
 		pad.Set(dse(7))

-	case pinModeUARTTX:
+	case PinModeUARTTX:
 		pad.Set(sre | dse(3) | spd(3))

-	case pinModeUARTRX:
+	case PinModeUARTRX:
 		pad.Set(dse(7) | pke | pue | pup(3) | hys)

-	case pinModeSPISDI:
+	case PinModeSPISDI:
 		pad.Set(dse(7) | spd(2))

-	case pinModeSPISDO:
+	case PinModeSPISDO:
 		pad.Set(dse(7) | spd(2))

-	case pinModeSPICLK:
+	case PinModeSPICLK:
 		pad.Set(dse(7) | spd(2))

-	case pinModeSPICS:
+	case PinModeSPICS:
 		pad.Set(dse(7))

-	case pinModeI2CSDA, pinModeI2CSCL:
+	case PinModeI2CSDA, PinModeI2CSCL:
 		pad.Set(ode | sre | dse(4) | spd(1) | pke | pue | pup(3))
 	}

@@ -391,7 +387,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
 	mask := p.getMask()
 	if nil != callback {
 		switch change {
-		case PinRising, PinFalling:
+		case PinLow, PinHigh, PinRising, PinFalling:
 			gpio.EDGE_SEL.ClearBits(mask)
 			var reg *volatile.Register32
 			var pos uint8
@@ -750,7 +746,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 	switch config.Mode {

 	// GPIO
-	case PinInput, PinInputPullup, PinInputPulldown,
+	case PinInput, PinInputPullUp, PinInputPullDown,
 		PinOutput, PinOutputOpenDrain, PinDisable:
 		mode := uint32(0x5) // GPIO is always alternate function 5
 		if forcePath {
@@ -759,7 +755,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// ADC
-	case pinInputAnalog:
+	case PinInputAnalog:
 		mode := uint32(0x5) // use alternate function 5 (GPIO)
 		if forcePath {
 			mode |= 0x10 // SION bit
@@ -767,7 +763,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// UART RX/TX
-	case pinModeUARTRX, pinModeUARTTX:
+	case PinModeUARTRX, PinModeUARTTX:
 		mode := uint32(0x2) // UART is usually alternate function 2 on Teensy 4.x
 		// Teensy 4.1 has a UART (LPUART5) with alternate function 1
 		if p == PB28 || p == PB29 {
@@ -776,7 +772,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// SPI SDI
-	case pinModeSPISDI:
+	case PinModeSPISDI:
 		var mode uint32
 		switch p {
 		case PC15: // LPSPI1 SDI on PC15 alternate function 4
@@ -794,7 +790,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// SPI SDO
-	case pinModeSPISDO:
+	case PinModeSPISDO:
 		var mode uint32
 		switch p {
 		case PC14: // LPSPI1 SDO on PC14 alternate function 4
@@ -812,7 +808,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// SPI SCK
-	case pinModeSPICLK:
+	case PinModeSPICLK:
 		var mode uint32
 		switch p {
 		case PC12: // LPSPI1 SCK on PC12 alternate function 4
@@ -830,7 +826,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// SPI CS
-	case pinModeSPICS:
+	case PinModeSPICS:
 		var mode uint32
 		switch p {
 		case PC13: // LPSPI1 CS on PC13 alternate function 4
@@ -848,7 +844,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// I2C SDA
-	case pinModeI2CSDA:
+	case PinModeI2CSDA:
 		var mode uint32
 		switch p {
 		case PA13: // LPI2C4 SDA on PA13 alternate function 0
@@ -866,7 +862,7 @@ func (p Pin) getMuxMode(config PinConfig) uint32 {
 		return mode

 	// I2C SCL
-	case pinModeI2CSCL:
+	case PinModeI2CSCL:
 		var mode uint32
 		switch p {
 		case PA12: // LPI2C4 SCL on PA12 alternate function 0
@@ -902,7 +898,7 @@ func (a ADC) Configure(config ADCConfig) {
 		defaultSamples    = uint32(4)
 	)

-	a.Pin.Configure(PinConfig{Mode: pinInputAnalog})
+	a.Pin.Configure(PinConfig{Mode: PinInputAnalog})

 	resolution, samples := config.Resolution, config.Samples
 	if 0 == resolution {
@@ -10,6 +10,15 @@ import (
 	"errors"
 )

+const (
+	TWI_FREQ_BUS     = 24000000        // LPI2C root clock is on 24 MHz OSC
+	TWI_FREQ_100KHZ  = 100000          // StandardMode (100 kHz)
+	TWI_FREQ_400KHZ  = 400000          // FastMode (400 kHz)
+	TWI_FREQ_1MHZ    = 1000000         // FastModePlus (1 MHz)
+	TWI_FREQ_5MHZ    = 5000000         // UltraFastMode (5 MHz)
+	TWI_FREQ_DEFAULT = TWI_FREQ_100KHZ // default to StandardMode (100 kHz)
+)
+
 var (
 	errI2CWriteTimeout       = errors.New("I2C timeout during write")
 	errI2CReadTimeout        = errors.New("I2C timeout during read")
@@ -156,8 +165,8 @@ func (i2c *I2C) Configure(config I2CConfig) {
 	sda, scl := i2c.setPins(config)

 	// configure the mux and pad control registers
-	sda.Configure(PinConfig{Mode: pinModeI2CSDA})
-	scl.Configure(PinConfig{Mode: pinModeI2CSCL})
+	sda.Configure(PinConfig{Mode: PinModeI2CSDA})
+	scl.Configure(PinConfig{Mode: PinModeI2CSCL})

 	// configure the mux input selector
 	i2c.muxSDA.connect()
@@ -165,7 +174,7 @@ func (i2c *I2C) Configure(config I2CConfig) {

 	freq := config.Frequency
 	if 0 == freq {
-		freq = 100 * KHz
+		freq = TWI_FREQ_DEFAULT
 	}

 	// reset clock and registers, and enable LPI2C module interface
@@ -296,7 +305,7 @@ func (i2c *I2C) setFrequency(freq uint32) {
 	wasEnabled := i2c.Bus.MCR.HasBits(nxp.LPI2C_MCR_MEN)
 	i2c.Bus.MCR.ClearBits(nxp.LPI2C_MCR_MEN)

-	// baud rate = (24MHz/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
+	// baud rate = (TWI_FREQ_BUS/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
 	// assume: CLKLO=2*CLKHI, SETHOLD=CLKHI, DATAVD=CLKHI/2
 	for pre := uint32(1); pre <= 128; pre *= 2 {
 		if bestError == 0 {
@@ -305,9 +314,9 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		for clkHi := uint32(1); clkHi < 32; clkHi++ {
 			var absError, rate uint32
 			if clkHi == 1 {
-				rate = (24 * MHz / pre) / (1 + 3 + 2 + 2/pre)
+				rate = (TWI_FREQ_BUS / pre) / (1 + 3 + 2 + 2/pre)
 			} else {
-				rate = (24 * MHz / pre) / (3*clkHi + 2 + 2/pre)
+				rate = (TWI_FREQ_BUS / pre) / (3*clkHi + 2 + 2/pre)
 			}
 			if freq > rate {
 				absError = freq - rate
@@ -361,15 +370,15 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		mcfgr2, mcfgr3 uint32
 	)
 	const i2cClockStretchTimeout = 15000 // microseconds
-	if freq >= 5*MHz {
+	if freq >= TWI_FREQ_5MHZ {
 		// I2C UltraFastMode 5 MHz
 		mcfgr2 = 0 // disable glitch filters and timeout for UltraFastMode
 		mcfgr3 = 0 //
-	} else if freq >= 1*MHz {
+	} else if freq >= TWI_FREQ_1MHZ {
 		// I2C FastModePlus 1 MHz
 		mcfgr2 = filtsda(1) | filtscl(1) | busidle(2400) // 100us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
-	} else if freq >= 400*KHz {
+	} else if freq >= TWI_FREQ_400KHZ {
 		// I2C FastMode 400 kHz
 		mcfgr2 = filtsda(2) | filtscl(2) | busidle(3600) // 150us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
@@ -77,10 +77,10 @@ func (spi *SPI) Configure(config SPIConfig) {
 	spi.sdi, spi.sdo, spi.sck, spi.cs = config.getPins()

 	// configure the mux and pad control registers
-	spi.sdi.Configure(PinConfig{Mode: pinModeSPISDI})
-	spi.sdo.Configure(PinConfig{Mode: pinModeSPISDO})
-	spi.sck.Configure(PinConfig{Mode: pinModeSPICLK})
-	spi.cs.Configure(PinConfig{Mode: pinModeSPICS})
+	spi.sdi.Configure(PinConfig{Mode: PinModeSPISDI})
+	spi.sdo.Configure(PinConfig{Mode: PinModeSPISDO})
+	spi.sck.Configure(PinConfig{Mode: PinModeSPICLK})
+	spi.cs.Configure(PinConfig{Mode: PinModeSPICS})

 	// configure the mux input selector
 	spi.muxSDI.connect()
@@ -68,8 +68,8 @@ func (uart *UART) Configure(config UARTConfig) {
 	uart.tx = config.TX

 	// configure the mux and pad control registers
-	uart.rx.Configure(PinConfig{Mode: pinModeUARTRX})
-	uart.tx.Configure(PinConfig{Mode: pinModeUARTTX})
+	uart.rx.Configure(PinConfig{Mode: PinModeUARTRX})
+	uart.tx.Configure(PinConfig{Mode: PinModeUARTTX})

 	// configure the mux input selector
 	uart.muxRX.connect()
@@ -159,8 +159,8 @@ func (uart *UART) Disable() {
 		uart.Bus.CTRL.ClearBits(nxp.LPUART_CTRL_TE | nxp.LPUART_CTRL_RE)

 		// put pins back into GPIO mode
-		uart.rx.Configure(PinConfig{Mode: PinInputPullup})
-		uart.tx.Configure(PinConfig{Mode: PinInputPullup})
+		uart.rx.Configure(PinConfig{Mode: PinInputPullUp})
+		uart.tx.Configure(PinConfig{Mode: PinInputPullUp})
 	}
 	uart.configured = false
 }
@@ -5,10 +5,15 @@ package machine

 import (
 	"device/nrf"
+	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )

+var (
+	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
+)
+
 const deviceName = nrf.Device

 const (
@@ -225,7 +230,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {

 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}
 	// Default I2C pins if not set.
 	if config.SDA == 0 && config.SCL == 0 {
@@ -248,7 +253,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 		(nrf.GPIO_PIN_CNF_DRIVE_S0D1 << nrf.GPIO_PIN_CNF_DRIVE_Pos) |
 		(nrf.GPIO_PIN_CNF_SENSE_Disabled << nrf.GPIO_PIN_CNF_SENSE_Pos))

-	if config.Frequency >= 400*KHz {
+	if config.Frequency == TWI_FREQ_400KHZ {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K400)
 	} else {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K100)
@@ -345,41 +350,3 @@ func (i2c *I2C) readByte() (byte, error) {
 	i2c.Bus.EVENTS_RXDREADY.Set(0)
 	return byte(i2c.Bus.RXD.Get()), nil
 }
-
-var rngStarted = false
-
-// GetRNG returns 32 bits of non-deterministic random data based on internal thermal noise.
-// According to Nordic's documentation, the random output is suitable for cryptographic purposes.
-func GetRNG() (ret uint32, err error) {
-	// There's no apparent way to check the status of the RNG peripheral's task, so simply start it
-	// to avoid deadlocking while waiting for output.
-	if !rngStarted {
-		nrf.RNG.TASKS_START.Set(1)
-		nrf.RNG.SetCONFIG_DERCEN(nrf.RNG_CONFIG_DERCEN_Enabled)
-		rngStarted = true
-	}
-
-	// The RNG returns one byte at a time, so stack up four bytes into a single uint32 for return.
-	for i := 0; i < 4; i++ {
-		// Wait for data to be ready.
-		for nrf.RNG.EVENTS_VALRDY.Get() == 0 {
-		}
-		// Append random byte to output.
-		ret = (ret << 8) ^ nrf.RNG.GetVALUE()
-		// Unset the EVENTS_VALRDY register to avoid reading the same random output twice.
-		nrf.RNG.EVENTS_VALRDY.Set(0)
-	}
-
-	return ret, nil
-}
-
-// ReadTemperature reads the silicon die temperature of the chip. The return
-// value is in milli-celsius.
-func ReadTemperature() int32 {
-	nrf.TEMP.TASKS_START.Set(1)
-	for nrf.TEMP.EVENTS_DATARDY.Get() == 0 {
-	}
-	temp := int32(nrf.TEMP.TEMP.Get()) * 250 // the returned value is in units of 0.25°C
-	nrf.TEMP.EVENTS_DATARDY.Set(0)
-	return temp
-}
@@ -9,16 +9,16 @@ import (
 )

 const (
-	dfuMagicSerialOnlyReset = 0x4e
-	dfuMagicUF2Reset        = 0x57
-	dfuMagicOTAReset        = 0xA8
+	DFU_MAGIC_SERIAL_ONLY_RESET = 0x4e
+	DFU_MAGIC_UF2_RESET         = 0x57
+	DFU_MAGIC_OTA_RESET         = 0xA8
 )

 // EnterSerialBootloader resets the chip into the serial bootloader. After
 // reset, it can be flashed using serial/nrfutil.
 func EnterSerialBootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(dfuMagicSerialOnlyReset)
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_SERIAL_ONLY_RESET)
 	arm.SystemReset()
 }

@@ -26,7 +26,7 @@ func EnterSerialBootloader() {
 // can be flashed via nrfutil or by copying a UF2 file to the mass storage device
 func EnterUF2Bootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(dfuMagicUF2Reset)
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_UF2_RESET)
 	arm.SystemReset()
 }

@@ -34,6 +34,6 @@ func EnterUF2Bootloader() {
 // flashed via an OTA update
 func EnterOTABootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(dfuMagicOTAReset)
+	nrf.POWER.GPREGRET.Set(DFU_MAGIC_OTA_RESET)
 	arm.SystemReset()
 }
@@ -42,19 +42,13 @@ const deviceName = nxp.Device

 const (
 	PinInput PinMode = iota
-	PinInputPullup
-	PinInputPulldown
+	PinInputPullUp
+	PinInputPullDown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable
 )

-// Deprecated: use PinInputPullup and PinInputPulldown instead.
-const (
-	PinInputPullUp   = PinInputPullup
-	PinInputPullDown = PinInputPulldown
-)
-
 const (
 	PA00 Pin = iota
 	PA01
@@ -229,11 +223,11 @@ func (p Pin) Configure(config PinConfig) {
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos))

-	case PinInputPullup:
+	case PinInputPullUp:
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos) | nxp.PORT_PCR0_PE | nxp.PORT_PCR0_PS)

-	case PinInputPulldown:
+	case PinInputPullDown:
 		gpio.PDDR.ClearBits(1 << pos)
 		pcr.Set((1 << nxp.PORT_PCR0_MUX_Pos) | nxp.PORT_PCR0_PE)

@@ -203,8 +203,8 @@ func (u *UART) Disable() {
 	u.C2.Set(0)

 	// reconfigure pin
-	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullup})
-	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullup})
+	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullUp})
+	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullUp})

 	// clear flags
 	u.S1.Get()
@@ -11,36 +11,36 @@ const deviceName = rp.Device

 const (
 	// GPIO pins
-	GPIO0  Pin = 0  // peripherals: PWM0 channel A
-	GPIO1  Pin = 1  // peripherals: PWM0 channel B
-	GPIO2  Pin = 2  // peripherals: PWM1 channel A
-	GPIO3  Pin = 3  // peripherals: PWM1 channel B
-	GPIO4  Pin = 4  // peripherals: PWM2 channel A
-	GPIO5  Pin = 5  // peripherals: PWM2 channel B
-	GPIO6  Pin = 6  // peripherals: PWM3 channel A
-	GPIO7  Pin = 7  // peripherals: PWM3 channel B
-	GPIO8  Pin = 8  // peripherals: PWM4 channel A
-	GPIO9  Pin = 9  // peripherals: PWM4 channel B
-	GPIO10 Pin = 10 // peripherals: PWM5 channel A
-	GPIO11 Pin = 11 // peripherals: PWM5 channel B
-	GPIO12 Pin = 12 // peripherals: PWM6 channel A
-	GPIO13 Pin = 13 // peripherals: PWM6 channel B
-	GPIO14 Pin = 14 // peripherals: PWM7 channel A
-	GPIO15 Pin = 15 // peripherals: PWM7 channel B
-	GPIO16 Pin = 16 // peripherals: PWM0 channel A
-	GPIO17 Pin = 17 // peripherals: PWM0 channel B
-	GPIO18 Pin = 18 // peripherals: PWM1 channel A
-	GPIO19 Pin = 19 // peripherals: PWM1 channel B
-	GPIO20 Pin = 20 // peripherals: PWM2 channel A
-	GPIO21 Pin = 21 // peripherals: PWM2 channel B
-	GPIO22 Pin = 22 // peripherals: PWM3 channel A
-	GPIO23 Pin = 23 // peripherals: PWM3 channel B
-	GPIO24 Pin = 24 // peripherals: PWM4 channel A
-	GPIO25 Pin = 25 // peripherals: PWM4 channel B
-	GPIO26 Pin = 26 // peripherals: PWM5 channel A
-	GPIO27 Pin = 27 // peripherals: PWM5 channel B
-	GPIO28 Pin = 28 // peripherals: PWM6 channel A
-	GPIO29 Pin = 29 // peripherals: PWM6 channel B
+	GPIO0  Pin = 0
+	GPIO1  Pin = 1
+	GPIO2  Pin = 2
+	GPIO3  Pin = 3
+	GPIO4  Pin = 4
+	GPIO5  Pin = 5
+	GPIO6  Pin = 6
+	GPIO7  Pin = 7
+	GPIO8  Pin = 8
+	GPIO9  Pin = 9
+	GPIO10 Pin = 10
+	GPIO11 Pin = 11
+	GPIO12 Pin = 12
+	GPIO13 Pin = 13
+	GPIO14 Pin = 14
+	GPIO15 Pin = 15
+	GPIO16 Pin = 16
+	GPIO17 Pin = 17
+	GPIO18 Pin = 18
+	GPIO19 Pin = 19
+	GPIO20 Pin = 20
+	GPIO21 Pin = 21
+	GPIO22 Pin = 22
+	GPIO23 Pin = 23
+	GPIO24 Pin = 24
+	GPIO25 Pin = 25
+	GPIO26 Pin = 26
+	GPIO27 Pin = 27
+	GPIO28 Pin = 28
+	GPIO29 Pin = 29

 	// Analog pins
 	ADC0 Pin = GPIO26
@@ -17,8 +17,8 @@ const (
 	adc0_CH ADCChannel = iota
 	adc1_CH
 	adc2_CH
-	adc3_CH       // Note: GPIO29 not broken out on pico board
-	adcTempSensor // Internal temperature sensor channel
+	adc3_CH         // Note: GPIO29 not broken out on pico board
+	ADC_TEMP_SENSOR // Internal temperature sensor channel
 )

 // Used to serialise ADC sampling
@@ -75,17 +75,19 @@ func (a ADC) GetADCChannel() (c ADCChannel, err error) {
 	return c, err
 }

-// Configure sets the channel's associated pin to analog input mode.
+// Configure sets the channel's associated pin to analog input mode or powers on the temperature sensor for ADC_TEMP_SENSOR.
 // The powered on temperature sensor increases ADC_AVDD current by approximately 40 μA.
 func (c ADCChannel) Configure(config ADCConfig) error {
 	if config.Reference != 0 {
 		adcAref = config.Reference
 	}
-	p, err := c.Pin()
-	if err != nil {
-		return err
+	if p, err := c.Pin(); err == nil {
+		p.Configure(PinConfig{Mode: PinAnalog})
+	}
+	if c == ADC_TEMP_SENSOR {
+		// Enable temperature sensor bias source
+		rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
 	}
-	p.Configure(PinConfig{Mode: pinAnalog})
 	return nil
 }

@@ -110,16 +112,13 @@ func (c ADCChannel) getVoltage() uint32 {
 }

 // ReadTemperature does a one-shot sample of the internal temperature sensor and returns a milli-celsius reading.
-func ReadTemperature() (millicelsius int32) {
-	if rp.ADC.CS.Get()&rp.ADC_CS_EN == 0 {
-		InitADC()
+// Only works on the ADC_TEMP_SENSOR channel. aka AINSEL=4. Other channels will return 0
+func (c ADCChannel) ReadTemperature() (millicelsius uint32) {
+	if c != ADC_TEMP_SENSOR {
+		return
 	}
-
-	// Enable temperature sensor bias source
-	rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
-
 	// T = 27 - (ADC_voltage - 0.706)/0.001721
-	return (27000<<16 - (int32(adcTempSensor.getVoltage())-706<<16)*581) >> 16
+	return (27000<<16 - (c.getVoltage()-706<<16)*581) >> 16
 }

 // waitForReady spins waiting for the ADC peripheral to become ready.
@@ -10,6 +10,11 @@ import (
 	"unsafe"
 )

+const (
+	KHz = 1000
+	MHz = 1000000
+)
+
 func CPUFrequency() uint32 {
 	return 125 * MHz
 }
@@ -81,13 +81,11 @@ const (
 	PinInput
 	PinInputPulldown
 	PinInputPullup
-
-	// internal pin modes
-	pinAnalog
-	pinUART
-	pinPWM
-	pinI2C
-	pinSPI
+	PinAnalog
+	PinUART
+	PinPWM
+	PinI2C
+	PinSPI
 )

 func (p Pin) PortMaskSet() (*uint32, uint32) {
@@ -190,20 +188,20 @@ func (p Pin) Configure(config PinConfig) {
 	case PinInputPullup:
 		p.setFunc(fnSIO)
 		p.pullup()
-	case pinAnalog:
+	case PinAnalog:
 		p.setFunc(fnNULL)
 		p.pulloff()
-	case pinUART:
+	case PinUART:
 		p.setFunc(fnUART)
-	case pinPWM:
+	case PinPWM:
 		p.setFunc(fnPWM)
-	case pinI2C:
+	case PinI2C:
 		// IO config according to 4.3.1.3 of rp2040 datasheet.
 		p.setFunc(fnI2C)
 		p.pullup()
 		p.setSchmitt(true)
 		p.setSlew(false)
-	case pinSPI:
+	case PinSPI:
 		p.setFunc(fnSPI)
 	}
 }
@@ -228,8 +226,12 @@ type PinChange uint8

 // Pin change interrupt constants for SetInterrupt.
 const (
+	// PinLevelLow triggers whenever pin is at a low (around 0V) logic level.
+	PinLevelLow PinChange = 1 << iota
+	// PinLevelLow triggers whenever pin is at a high (around 3V) logic level.
+	PinLevelHigh
 	// Edge falling
-	PinFalling PinChange = 4 << iota
+	PinFalling
 	// Edge rising
 	PinRising
 )
@@ -105,8 +105,8 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 	if config.Frequency == 0 {
 		config.Frequency = defaultBaud
 	}
-	config.SDA.Configure(PinConfig{pinI2C})
-	config.SCL.Configure(PinConfig{pinI2C})
+	config.SDA.Configure(PinConfig{PinI2C})
+	config.SCL.Configure(PinConfig{PinI2C})
 	return i2c.init(config)
 }

@@ -92,7 +92,7 @@ func (pwm *pwmGroup) Channel(pin Pin) (channel uint8, err error) {
 	if pin > maxPWMPins || pwmGPIOToSlice(pin) != pwm.peripheral() {
 		return 3, ErrInvalidOutputPin
 	}
-	pin.Configure(PinConfig{pinPWM})
+	pin.Configure(PinConfig{PinPWM})
 	return pwmGPIOToChannel(pin), nil
 }

@@ -1,42 +0,0 @@
-//go:build rp2040
-// +build rp2040
-
-// Implementation based on code located here:
-// https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/pico_lwip/random.c
-
-package machine
-
-import (
-	"device/rp"
-)
-
-const numberOfCycles = 32
-
-// GetRNG returns 32 bits of semi-random data based on ring oscillator.
-//
-// Unlike some other implementations of GetRNG, these random numbers are not
-// cryptographically secure and must not be used for cryptographic operations
-// (nonces, etc).
-func GetRNG() (uint32, error) {
-	var val uint32
-	for i := 0; i < 4; i++ {
-		val = (val << 8) | uint32(roscRandByte())
-	}
-	return val, nil
-}
-
-var randomByte uint8
-
-func roscRandByte() uint8 {
-	var poly uint8
-	for i := 0; i < numberOfCycles; i++ {
-		if randomByte&0x80 != 0 {
-			poly = 0x35
-		} else {
-			poly = 0
-		}
-		randomByte = ((randomByte << 1) | uint8(rp.ROSC.GetRANDOMBIT()) ^ poly)
-		// TODO: delay a little because the random bit is a little slow
-	}
-	return randomByte
-}
@@ -38,9 +38,10 @@ type SPIConfig struct {
 }

 var (
-	ErrLSBNotSupported = errors.New("SPI LSB unsupported on PL022")
-	ErrSPITimeout      = errors.New("SPI timeout")
-	ErrSPIBaud         = errors.New("SPI baud too low or above 66.5Mhz")
+	ErrLSBNotSupported    = errors.New("SPI LSB unsupported on PL022")
+	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
+	ErrSPITimeout         = errors.New("SPI timeout")
+	ErrSPIBaud            = errors.New("SPI baud too low or above 66.5Mhz")
 )

 type SPI struct {
@@ -42,8 +42,8 @@ func (uart *UART) Configure(config UARTConfig) error {
 		rp.UART0_UARTCR_TXE)

 	// set GPIO mux to UART for the pins
-	config.TX.Configure(PinConfig{Mode: pinUART})
-	config.RX.Configure(PinConfig{Mode: pinUART})
+	config.TX.Configure(PinConfig{Mode: PinUART})
+	config.RX.Configure(PinConfig{Mode: PinUART})

 	// Enable RX IRQ.
 	uart.Interrupt.SetPriority(0x80)
@@ -41,7 +41,7 @@ func InitADC() {

 // Configure configures an ADC pin to be able to read analog data.
 func (a ADC) Configure(ADCConfig) {
-	a.Pin.Configure(PinConfig{Mode: pinInputModeAnalog})
+	a.Pin.Configure(PinConfig{Mode: PinInputModeAnalog})

 	// set sample time
 	ch := a.getChannel()
@@ -36,7 +36,7 @@ func InitADC() {

 // Configure configures an ADC pin to be able to read analog data.
 func (a ADC) Configure(ADCConfig) {
-	a.Pin.ConfigureAltFunc(PinConfig{Mode: pinInputAnalog}, 0)
+	a.Pin.ConfigureAltFunc(PinConfig{Mode: PinInputAnalog}, 0)

 	// set sample time
 	ch := a.getChannel()
@@ -137,7 +137,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {

 	// default to 100 kHz (Sm, standard mode) if no frequency is set
 	if config.Frequency == 0 {
-		config.Frequency = 100 * KHz
+		config.Frequency = TWI_FREQ_100KHZ
 	}

 	// configure I2C input clock
@@ -102,8 +102,8 @@ func (i2c *I2C) Tx(addr uint16, w, r []byte) error {
 }

 func (i2c *I2C) configurePins(config I2CConfig) {
-	config.SCL.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSCL}, i2c.AltFuncSelector)
-	config.SDA.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSDA}, i2c.AltFuncSelector)
+	config.SCL.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSCL}, i2c.AltFuncSelector)
+	config.SDA.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSDA}, i2c.AltFuncSelector)
 }

 func (i2c *I2C) controllerTransmit(addr uint16, w []byte) error {
@@ -14,28 +14,29 @@ import (
 const (
 	// Mode Flag
 	PinOutput        PinMode = 0
-	PinInput         PinMode = 1
+	PinInput         PinMode = PinInputFloating
+	PinInputFloating PinMode = 1
 	PinInputPulldown PinMode = 2
 	PinInputPullup   PinMode = 3

 	// for UART
-	pinModeUARTTX PinMode = 4
-	pinModeUARTRX PinMode = 5
+	PinModeUARTTX PinMode = 4
+	PinModeUARTRX PinMode = 5

 	// for I2C
-	pinModeI2CSCL PinMode = 6
-	pinModeI2CSDA PinMode = 7
+	PinModeI2CSCL PinMode = 6
+	PinModeI2CSDA PinMode = 7

 	// for SPI
-	pinModeSPICLK PinMode = 8
-	pinModeSPISDO PinMode = 9
-	pinModeSPISDI PinMode = 10
+	PinModeSPICLK PinMode = 8
+	PinModeSPISDO PinMode = 9
+	PinModeSPISDI PinMode = 10

 	// for analog/ADC
-	pinInputAnalog PinMode = 11
+	PinInputAnalog PinMode = 11

 	// for PWM
-	pinModePWMOutput PinMode = 12
+	PinModePWMOutput PinMode = 12
 )

 // Define several bitfields that have different names across chip families but
@@ -82,7 +83,7 @@ func (p Pin) ConfigureAltFunc(config PinConfig, altFunc uint8) {
 	switch config.Mode {

 	// GPIO
-	case PinInput:
+	case PinInputFloating:
 		port.MODER.ReplaceBits(gpioModeInput, gpioModeMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 	case PinInputPulldown:
@@ -96,24 +97,24 @@ func (p Pin) ConfigureAltFunc(config PinConfig, altFunc uint8) {
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedHigh, gpioOutputSpeedMask, pos)

 	// UART
-	case pinModeUARTTX:
+	case PinModeUARTTX:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedHigh, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullUp, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)
-	case pinModeUARTRX:
+	case PinModeUARTRX:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)

 	// I2C
-	case pinModeI2CSCL:
+	case PinModeI2CSCL:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OTYPER.ReplaceBits(stm32.GPIO_OTYPER_OT0_OpenDrain, stm32.GPIO_OTYPER_OT0_Msk, pos/2)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedLow, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullUp, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)
-	case pinModeI2CSDA:
+	case PinModeI2CSDA:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OTYPER.ReplaceBits(stm32.GPIO_OTYPER_OT0_OpenDrain, stm32.GPIO_OTYPER_OT0_Msk, pos/2)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedLow, gpioOutputSpeedMask, pos)
@@ -121,31 +122,31 @@ func (p Pin) ConfigureAltFunc(config PinConfig, altFunc uint8) {
 		p.SetAltFunc(altFunc)

 	// SPI
-	case pinModeSPICLK:
+	case PinModeSPICLK:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedHigh, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)
-	case pinModeSPISDO:
+	case PinModeSPISDO:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedLow, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)
-	case pinModeSPISDI:
+	case PinModeSPISDI:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedLow, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)

 	// PWM
-	case pinModePWMOutput:
+	case PinModePWMOutput:
 		port.MODER.ReplaceBits(gpioModeAlternate, gpioModeMask, pos)
 		port.OSPEEDR.ReplaceBits(gpioOutputSpeedHigh, gpioOutputSpeedMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 		p.SetAltFunc(altFunc)

 	// ADC
-	case pinInputAnalog:
+	case PinInputAnalog:
 		port.MODER.ReplaceBits(gpioModeAnalog, gpioModeMask, pos)
 	}
 }
@@ -183,7 +183,7 @@ func (t *TIM) Channel(pin Pin) (uint8, error) {
 		for _, p := range ch.Pins {
 			if p.Pin == pin {
 				t.configurePin(uint8(chi), p)
-				//p.Pin.ConfigureAltFunc(PinConfig{Mode: pinModePWMOutput}, p.AltFunc)
+				//p.Pin.ConfigureAltFunc(PinConfig{Mode: PinModePWMOutput}, p.AltFunc)
 				return uint8(chi), nil
 			}
 		}
@@ -7,5 +7,5 @@ package machine
 // register (most MCUs except STM32F1 series).

 func (t *TIM) configurePin(channel uint8, pf PinFunction) {
-	pf.Pin.ConfigureAltFunc(PinConfig{Mode: pinModePWMOutput}, pf.AltFunc)
+	pf.Pin.ConfigureAltFunc(PinConfig{Mode: PinModePWMOutput}, pf.AltFunc)
 }
@@ -29,20 +29,20 @@ const (
 	PinOutput50MHz PinMode = 3 // Output mode, max speed 50MHz
 	PinOutput      PinMode = PinOutput2MHz

-	pinInputModeAnalog     PinMode = 0  // Input analog mode
-	pinInputModeFloating   PinMode = 4  // Input floating mode
-	pinInputModePullUpDown PinMode = 8  // Input pull up/down mode
-	pinInputModeReserved   PinMode = 12 // Input mode (reserved)
+	PinInputModeAnalog     PinMode = 0  // Input analog mode
+	PinInputModeFloating   PinMode = 4  // Input floating mode
+	PinInputModePullUpDown PinMode = 8  // Input pull up/down mode
+	PinInputModeReserved   PinMode = 12 // Input mode (reserved)

-	pinOutputModeGPPushPull   PinMode = 0  // Output mode general purpose push/pull
-	pinOutputModeGPOpenDrain  PinMode = 4  // Output mode general purpose open drain
-	pinOutputModeAltPushPull  PinMode = 8  // Output mode alt. purpose push/pull
-	pinOutputModeAltOpenDrain PinMode = 12 // Output mode alt. purpose open drain
+	PinOutputModeGPPushPull   PinMode = 0  // Output mode general purpose push/pull
+	PinOutputModeGPOpenDrain  PinMode = 4  // Output mode general purpose open drain
+	PinOutputModeAltPushPull  PinMode = 8  // Output mode alt. purpose push/pull
+	PinOutputModeAltOpenDrain PinMode = 12 // Output mode alt. purpose open drain

 	// Pull-up vs Pull down is not part of the CNF0 / CNF1 bits, but is
 	// controlled by PxODR.  Encoded using the 'spare' bit 5.
-	PinInputPulldown PinMode = pinInputModePullUpDown
-	PinInputPullup   PinMode = pinInputModePullUpDown | 0x10
+	PinInputPulldown PinMode = PinInputModePullUpDown
+	PinInputPullup   PinMode = PinInputModePullUpDown | 0x10
 )

 // Pin constants for all stm32f103 package sizes
@@ -166,7 +166,7 @@ func (p Pin) Configure(config PinConfig) {

 	// If configured for input pull-up or pull-down, set ODR
 	// for desired pull-up or pull-down.
-	if (config.Mode & 0xf) == pinInputModePullUpDown {
+	if (config.Mode & 0xf) == PinInputModePullUpDown {
 		var pullup uint32
 		if config.Mode == PinInputPullup {
 			pullup = 1
@@ -290,8 +290,8 @@ func (uart *UART) configurePins(config UARTConfig) {
 	default:
 		// use standard TX/RX pins PA9 and PA10
 	}
-	config.TX.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.RX.Configure(PinConfig{Mode: pinInputModeFloating})
+	config.TX.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
+	config.RX.Configure(PinConfig{Mode: PinInputModeFloating})
 }

 // Determine the divisor for USARTs to get the given baudrate
@@ -363,9 +363,9 @@ func (spi SPI) getBaudRate(config SPIConfig) uint32 {

 // Configure SPI pins for input output and clock
 func (spi SPI) configurePins(config SPIConfig) {
-	config.SCK.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.SDO.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.SDI.Configure(PinConfig{Mode: pinInputModeFloating})
+	config.SCK.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
+	config.SDO.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
+	config.SDI.Configure(PinConfig{Mode: PinInputModeFloating})
 }

 //---------- I2C related types and code
@@ -390,8 +390,8 @@ func (i2c *I2C) configurePins(config I2CConfig) {
 		stm32.AFIO.MAPR.SetBits(stm32.AFIO_MAPR_I2C1_REMAP)
 	}

-	config.SDA.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltOpenDrain})
-	config.SCL.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltOpenDrain})
+	config.SDA.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltOpenDrain})
+	config.SCL.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltOpenDrain})
 }

 func (i2c *I2C) getFreqRange(config I2CConfig) uint32 {
@@ -717,7 +717,7 @@ func (t *TIM) configurePin(channel uint8, pf PinFunction) {
 		stm32.AFIO.MAPR.ReplaceBits(remap<<stm32.AFIO_MAPR2_TIM14_REMAP_Pos, stm32.AFIO_MAPR2_TIM14_REMAP_Msk, 0)
 	}

-	pf.Pin.Configure(PinConfig{Mode: PinOutput + pinOutputModeAltPushPull})
+	pf.Pin.Configure(PinConfig{Mode: PinOutput + PinOutputModeAltPushPull})
 }

 func (t *TIM) enableMainOutput() {
@@ -640,8 +640,8 @@ const (

 func (uart *UART) configurePins(config UARTConfig) {
 	// enable the alternate functions on the TX and RX pins
-	config.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
+	config.TX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTTX}, uart.TxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
 }

 func (uart *UART) getBaudRateDivisor(baudRate uint32) uint32 {
@@ -674,9 +674,9 @@ func (spi SPI) config8Bits() {
 }

 func (spi SPI) configurePins(config SPIConfig) {
-	config.SCK.ConfigureAltFunc(PinConfig{Mode: pinModeSPICLK}, spi.AltFuncSelector)
-	config.SDO.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDO}, spi.AltFuncSelector)
-	config.SDI.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDI}, spi.AltFuncSelector)
+	config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
+	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
+	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, spi.AltFuncSelector)
 }

 func (spi SPI) getBaudRate(config SPIConfig) uint32 {
@@ -723,8 +723,8 @@ type I2C struct {
 }

 func (i2c *I2C) configurePins(config I2CConfig) {
-	config.SCL.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSCL}, i2c.AltFuncSelector)
-	config.SDA.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSDA}, i2c.AltFuncSelector)
+	config.SCL.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSCL}, i2c.AltFuncSelector)
+	config.SDA.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSDA}, i2c.AltFuncSelector)
 }

 func (i2c *I2C) getFreqRange(config I2CConfig) uint32 {
--- a/Show More
+++ b/Show More