machine: hide internal pin modes

Many pin modes are only for peripherals like SPI and PWM. Do not make
these part of the public API: the public API is the Configure method on
the peripheral, not the PinMode constant.

.circleci/config.yml

@@ -118,13 +118,7 @@ jobs:
     steps:
       - test-linux:
           llvm: "14"
-  test-llvm14-go119:
+    resource_class: large
-    docker:
-      - image: golang:1.19beta1-buster
-    steps:
-      - test-linux:
-          llvm: "14"
-          fmt-check: false
 
 workflows:
   test-all:
@@ -132,6 +126,3 @@ 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

.github/workflows/build-macos.yml

@@ -34,7 +34,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Cache LLVM source
         uses: actions/cache@v3
@@ -114,7 +114,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18'
+          go-version: '1.19'
           cache: true
       - name: Build TinyGo
         run: go install

.github/workflows/linux.yml

@@ -18,7 +18,7 @@ jobs:
     # statically linked binary.
     runs-on: ubuntu-latest
     container:
-      image: golang:1.18-alpine
+      image: golang:1.19-alpine
     steps:
       - name: Install apk dependencies
         # tar: needed for actions/cache@v3
@@ -118,7 +118,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Install wasmtime
         run: |
@@ -171,7 +171,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Install Node.js
         uses: actions/setup-node@v2
@@ -271,7 +271,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Cache LLVM source
         uses: actions/cache@v3
@@ -371,7 +371,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Cache LLVM source
         uses: actions/cache@v3

.github/workflows/windows.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18.1'
+          go-version: '1.19'
           cache: true
       - name: Cache LLVM source
         uses: actions/cache@v3

Dockerfile

@@ -1,5 +1,5 @@
 # tinygo-llvm stage obtains the llvm source for TinyGo
-FROM golang:1.18 AS tinygo-llvm
+FROM golang:1.19 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

Makefile

@@ -330,7 +330,6 @@ endif
 # 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/fs requires os.ReadDir, which is not yet supported on windows or wasi
 # 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
@@ -344,7 +343,6 @@ TEST_PACKAGES_LINUX := \
 	crypto/hmac \
 	debug/dwarf \
 	debug/plan9obj \
-	io/fs \
 	io/ioutil \
 	strconv \
 	testing/fstest \
@@ -373,12 +371,15 @@ 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.
@@ -386,6 +387,12 @@ 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 $(TEST_PACKAGES_HOST)
 tinygo-bench:
@@ -611,7 +618,7 @@ endif
 	@$(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/adc_rp2040
+	$(TINYGO) build -size short -o test.hex -target=trinkey-qt2040      examples/temp
 	@$(MD5SUM) test.hex
 	# test pwm
 	$(TINYGO) build -size short -o test.hex -target=itsybitsy-m0        examples/pwm

builder/build.go

@@ -178,7 +178,7 @@ func Build(pkgName, outpath string, config *compileopts.Config, action func(Buil
 
 		Scheduler:          config.Scheduler(),
 		AutomaticStackSize: config.AutomaticStackSize(),
-		DefaultStackSize:   config.Target.DefaultStackSize,
+		DefaultStackSize:   config.StackSize(),
 		NeedsStackObjects:  config.NeedsStackObjects(),
 		Debug:              true,
 	}

cgo/cgo.go

@@ -32,6 +32,7 @@ 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
@@ -39,12 +40,15 @@ 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
 }
@@ -158,9 +162,10 @@ 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 string, fset *token.FileSet, cflags []string, clangHeaders string) (*ast.File, []string, []string, []string, map[string][]byte, []error) {
+func Process(files []*ast.File, dir, importPath 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{},
@@ -210,13 +215,13 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 		}
 	}
 	// Patch some types, for example *C.char in C.CString.
-	cf := p.newCGoFile()
+	cf := p.newCGoFile(nil, -1) // dummy *cgoFile for the walker
 	astutil.Apply(p.generated, func(cursor *astutil.Cursor) bool {
 		return cf.walker(cursor, nil)
 	}, nil)
 
 	// Find `import "C"` C fragments in the file.
-	cgoHeaders := make([]string, len(files)) // combined CGo header fragment for each file
+	p.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++ {
@@ -275,7 +280,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 			cgoHeader += fragment
 		}
 
-		cgoHeaders[i] = cgoHeader
+		p.cgoHeaders[i] = cgoHeader
 	}
 
 	// Define CFlags that will be used while parsing the package.
@@ -289,7 +294,7 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	}
 
 	// Retrieve types such as C.int, C.longlong, etc from C.
-	p.newCGoFile().readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
+	p.newCGoFile(nil, -1).readNames(builtinAliasTypedefs, cflagsForCGo, "", func(names map[string]clangCursor) {
 		gen := &ast.GenDecl{
 			TokPos: token.NoPos,
 			Tok:    token.TYPE,
@@ -303,8 +308,8 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 
 	// Process CGo imports for each file.
 	for i, f := range files {
-		cf := p.newCGoFile()
+		cf := p.newCGoFile(f, i)
-		cf.readNames(cgoHeaders[i], cflagsForCGo, filepath.Base(fset.File(f.Pos()).Name()), func(names map[string]clangCursor) {
+		cf.readNames(p.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`
@@ -320,12 +325,14 @@ func Process(files []*ast.File, dir string, fset *token.FileSet, cflags []string
 	// Print the newly generated in-memory AST, for debugging.
 	//ast.Print(fset, p.generated)
 
-	return p.generated, cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
+	return p.generated, p.cgoHeaders, p.cflags, p.ldflags, p.visitedFiles, p.errors
 }
 
-func (p *cgoPackage) newCGoFile() *cgoFile {
+func (p *cgoPackage) newCGoFile(file *ast.File, index int) *cgoFile {
 	return &cgoFile{
 		cgoPackage: p,
+		file:       file,
+		index:      index,
 		defined:    make(map[string]ast.Node),
 		names:      make(map[string]clangCursor),
 	}
@@ -1117,8 +1124,11 @@ func (f *cgoFile) getASTDeclName(name string, found clangCursor, iscall bool) st
 		return alias
 	}
 	node := f.getASTDeclNode(name, found, iscall)
-	if _, ok := node.(*ast.FuncDecl); ok && !iscall {
+	if node, ok := node.(*ast.FuncDecl); ok {
-		return "C." + name + "$funcaddr"
+		if !iscall {
+			return node.Name.Name + "$funcaddr"
+		}
+		return node.Name.Name
 	}
 	return "C." + name
 }
@@ -1142,7 +1152,7 @@ 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), "defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
+			f.addError(getPos(node), name+" defined previously at "+f.fset.Position(getPos(newNode)).String()+" with a different type")
 		}
 		f.defined[name] = node
 		return node
@@ -1150,11 +1160,39 @@ 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, elaboratedType := f.createASTNode(name, found)
+	node, extra := 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$funcaddr unsafe.Pointer
@@ -1162,7 +1200,7 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			Tok: token.VAR,
 			Specs: []ast.Spec{
 				&ast.ValueSpec{
-					Names: []*ast.Ident{{Name: "C." + name + "$funcaddr"}},
+					Names: []*ast.Ident{{Name: node.Name.Name + "$funcaddr"}},
 					Type: &ast.SelectorExpr{
 						X:   &ast.Ident{Name: "unsafe"},
 						Sel: &ast.Ident{Name: "Pointer"},
@@ -1171,8 +1209,10 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 			},
 		})
 	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},
@@ -1186,7 +1226,8 @@ func (f *cgoFile) getASTDeclNode(name string, found clangCursor, iscall bool) as
 
 	// If this is a struct or union it may need bitfields or union accessor
 	// methods.
-	if elaboratedType != nil {
+	switch elaboratedType := extra.(type) {
+	case *elaboratedTypeInfo:
 		// Add struct bitfields.
 		for _, bitfield := range elaboratedType.bitfields {
 			f.createBitfieldGetter(bitfield, "C."+name)

cgo/cgo_test.go

@@ -48,7 +48,7 @@ func TestCGo(t *testing.T) {
 			}
 
 			// Process the AST with CGo.
-			cgoAST, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", fset, cflags, "")
+			cgoAST, _, _, _, _, cgoErrors := Process([]*ast.File{f}, "testdata", "main", fset, cflags, "")
 
 			// Check the AST for type errors.
 			var typecheckErrors []error

cgo/libclang.go

@@ -4,7 +4,9 @@ package cgo
 // modification. It does not touch the AST itself.
 
 import (
+	"crypto/sha256"
 	"crypto/sha512"
+	"encoding/hex"
 	"fmt"
 	"go/ast"
 	"go/scanner"
@@ -43,6 +45,8 @@ 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);
@@ -50,6 +54,7 @@ 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);
@@ -189,7 +194,7 @@ 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, *elaboratedTypeInfo) {
+func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, any) {
 	kind := C.tinygo_clang_getCursorKind(c)
 	pos := f.getCursorPosition(c)
 	switch kind {
@@ -200,19 +205,43 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaborat
 			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 " + name,
+						Text:  "//export " + exportName,
 					},
 				},
 			},
 			Name: &ast.Ident{
 				NamePos: pos,
-				Name:    "C." + name,
+				Name:    "C." + localName,
 				Obj:     obj,
 			},
 			Type: &ast.FuncType{
@@ -263,7 +292,7 @@ func (f *cgoFile) createASTNode(name string, c clangCursor) (ast.Node, *elaborat
 			}
 		}
 		obj.Decl = decl
-		return decl, nil
+		return decl, stringSignature
 	case C.CXCursor_StructDecl, C.CXCursor_UnionDecl:
 		typ := f.makeASTRecordType(c, pos)
 		typeName := "C." + name

cgo/libclang_stubs.c

@@ -17,6 +17,14 @@ 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);
 }
@@ -45,6 +53,10 @@ 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);
 }

cgo/security.go

@@ -142,7 +142,6 @@ var validLinkerFlags = []*regexp.Regexp{
 	re(`-L([^@\-].*)`),
 	re(`-O`),
 	re(`-O([^@\-].*)`),
-	re(`--export=(.+)`), // for wasm-ld
 	re(`-f(no-)?(pic|PIC|pie|PIE)`),
 	re(`-f(no-)?openmp(-simd)?`),
 	re(`-fsanitize=([^@\-].*)`),

cgo/testdata/symbols.go

@@ -5,6 +5,7 @@ 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;
@@ -16,6 +17,7 @@ func accessFunctions() {
 	C.foo(3, 4)
 	C.variadic0()
 	C.variadic2(3, 5)
+	C.staticfunc(3)
 }
 
 func accessGlobals() {

cgo/testdata/symbols.out.go

@@ -55,5 +55,10 @@ 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

compileopts/config.go

@@ -175,6 +175,15 @@ 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

compileopts/options.go

@@ -28,6 +28,7 @@ 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
@@ -49,6 +50,8 @@ 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.

compiler/compiler.go

@@ -1059,12 +1059,11 @@ func (b *builder) createFunctionStart(intrinsic bool) {
 	if b.info.section != "" {
 		b.llvmFn.SetSection(b.info.section)
 	}
-	if b.info.exported && b.info.module != "" && strings.HasPrefix(b.Triple, "wasm") {
+	if b.info.exported && strings.HasPrefix(b.Triple, "wasm") {
 		// Set the exported name. This is necessary for WebAssembly because
 		// otherwise the function is not exported.
-		b.llvmFn.AddFunctionAttr(b.ctx.CreateStringAttribute("wasm-export-name", b.info.linkName))
+		functionAttr := b.ctx.CreateStringAttribute("wasm-export-name", b.info.linkName)
-		// Set the export module.
+		b.llvmFn.AddFunctionAttr(functionAttr)
-		b.llvmFn.AddFunctionAttr(b.ctx.CreateStringAttribute("wasm-export-module", b.info.module))
 	}
 
 	// Some functions have a pragma controlling the inlining level.

compiler/compiler_test.go

@@ -79,7 +79,7 @@ func TestCompiler(t *testing.T) {
 				RelocationModel:    config.RelocationModel(),
 				Scheduler:          config.Scheduler(),
 				AutomaticStackSize: config.AutomaticStackSize(),
-				DefaultStackSize:   config.Target.DefaultStackSize,
+				DefaultStackSize:   config.StackSize(),
 				NeedsStackObjects:  config.NeedsStackObjects(),
 			}
 			machine, err := NewTargetMachine(compilerConfig)

compiler/symbol.go

@@ -210,9 +210,8 @@ func (c *compilerContext) getFunction(fn *ssa.Function) llvm.Value {
 // exported.
 func (c *compilerContext) getFunctionInfo(f *ssa.Function) functionInfo {
 	info := functionInfo{
-		module:     "env",
+		// Pick the default linkName.
-		importName: f.Name(),
+		linkName: f.RelString(nil),
-		linkName:   f.RelString(nil), // pick the default linkName
 	}
 	// Check for //go: pragmas, which may change the link name (among others).
 	info.parsePragmas(f)
@@ -226,6 +225,10 @@ func (info *functionInfo) parsePragmas(f *ssa.Function) {
 		return
 	}
 	if decl, ok := f.Syntax().(*ast.FuncDecl); ok && decl.Doc != nil {
+
+		// Our importName for a wasm module (if we are compiling to wasm), or llvm link name
+		var importName string
+
 		for _, comment := range decl.Doc.List {
 			text := comment.Text
 			if strings.HasPrefix(text, "//export ") {
@@ -243,8 +246,7 @@ func (info *functionInfo) parsePragmas(f *ssa.Function) {
 					continue
 				}
 
-				info.importName = parts[1]
+				importName = parts[1]
-				info.linkName = parts[1]
 				info.exported = true
 			case "//go:interrupt":
 				if hasUnsafeImport(f.Pkg.Pkg) {
@@ -252,13 +254,10 @@ func (info *functionInfo) parsePragmas(f *ssa.Function) {
 				}
 			case "//go:wasm-module":
 				// Alternative comment for setting the import module.
-				if len(parts) == 1 {
+				if len(parts) != 2 {
-					// Function must not be exported outside of the WebAssembly
+					continue
-					// module (but only be made available for linking).
-					info.module = ""
-				} else if len(parts) == 2 {
-					info.module = parts[1]
 				}
+				info.module = parts[1]
 			case "//go:inline":
 				info.inline = inlineHint
 			case "//go:noinline":
@@ -298,6 +297,17 @@ func (info *functionInfo) parsePragmas(f *ssa.Function) {
 				}
 			}
 		}
+
+		// Set the importName for our exported function if we have one
+		if importName != "" {
+			if info.module == "" {
+				info.linkName = importName
+			} else {
+				// WebAssembly import
+				info.importName = importName
+			}
+		}
+
 	}
 }
 

compiler/testdata/pragma.ll

@@ -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-module"="env" "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" "wasm-import-module"="env" "wasm-import-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-module"="env" "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" "wasm-import-module"="env" "wasm-import-name"="exportedFunctionInSection" }

go.mod

@@ -9,8 +9,10 @@ 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

go.sum

@@ -12,7 +12,6 @@ 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=
@@ -23,44 +22,47 @@ 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/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-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=

interp/interpreter.go

@@ -369,6 +369,11 @@ 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

loader/loader.go

@@ -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.program.fset, initialCFlags, p.program.clangHeaders)
+		generated, headerCode, cflags, ldflags, accessedFiles, errs := cgo.Process(files, p.program.workingDir, p.ImportPath, p.program.fset, initialCFlags, p.program.clangHeaders)
 		p.CFlags = append(initialCFlags, cflags...)
 		p.CGoHeaders = headerCode
 		for path, hash := range accessedFiles {

main.go

@@ -26,6 +26,7 @@ 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"
@@ -422,7 +423,6 @@ 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":
@@ -430,13 +430,11 @@ 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")
 			}
@@ -457,7 +455,6 @@ 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 {
@@ -476,10 +473,13 @@ 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
 	})
 }
 
@@ -998,7 +998,8 @@ 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 primaryPorts []string   // ports picked from preferred USB VID/PID
+		var secondaryPorts []string // other ports (as a fallback)
 		for _, p := range portsList {
 			if !p.IsUSB {
 				continue
@@ -1020,6 +1021,8 @@ 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
@@ -1031,18 +1034,10 @@ 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
-		if len(ports) == 0 {
+			// available in the system.
-			// fallback
+			ports = secondaryPorts
-			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")
@@ -1057,7 +1052,9 @@ func getDefaultPort(portFlag string, usbInterfaces []string) (port string, err e
 	}
 
 	if len(portCandidates) == 0 {
-		if len(ports) == 1 {
+		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 {
 			return ports[0], nil
 		} else {
 			return "", errors.New("multiple serial ports available - use -port flag, available ports are " + strings.Join(ports, ", "))
@@ -1122,6 +1119,7 @@ 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")+")")
@@ -1318,6 +1316,12 @@ 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")
@@ -1332,6 +1336,8 @@ 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" {
@@ -1398,6 +1404,7 @@ func main() {
 		GOARCH:          goenv.Get("GOARCH"),
 		GOARM:           goenv.Get("GOARM"),
 		Target:          *target,
+		StackSize:       stackSize,
 		Opt:             *opt,
 		GC:              *gc,
 		PanicStrategy:   *panicStrategy,
@@ -1420,6 +1427,8 @@ func main() {
 		OpenOCDCommands: ocdCommands,
 		LLVMFeatures:    *llvmFeatures,
 		PrintJSON:       flagJSON,
+		Monitor:         *monitor,
+		BaudRate:        *baudrate,
 	}
 	if *printCommands {
 		options.PrintCommands = printCommand
@@ -1610,6 +1619,9 @@ 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)

monitor.go

@@ -0,0 +1,106 @@
+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
+}

src/crypto/rand/rand_baremetal.go

@@ -1,5 +1,5 @@
-//go:build nrf52840 || stm32 || (sam && atsamd51) || (sam && atsame5x) || rp2040
+//go:build nrf || stm32 || (sam && atsamd51) || (sam && atsame5x)
-// +build nrf52840 stm32 sam,atsamd51 sam,atsame5x rp2040
+// +build nrf stm32 sam,atsamd51 sam,atsame5x
 
 package rand
 

src/examples/adc_rp2040/adc.go

@@ -1,49 +0,0 @@
-// 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)
-	}
-}

src/examples/temp/temp.go

@@ -0,0 +1,23 @@
+// 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)
+	}
+}

src/machine/board_arduino_mkr1000.go

@@ -7,7 +7,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135
 
 // GPIO Pins
 const (

src/machine/board_arduino_mkrwifi1010.go

@@ -7,7 +7,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135
 
 // GPIO Pins
 const (

src/machine/board_arduino_nano33.go

@@ -7,7 +7,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135
 
 // GPIO Pins
 const (

src/machine/board_arduino_zero.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135
 
 // GPIO Pins - Digital Low
 const (

src/machine/board_atsame54-xpro.go

@@ -8,7 +8,7 @@ import (
 )
 
 // Definition for compatibility, but not used
-const RESET_MAGIC_VALUE = 0x00000000
+const resetMagicValue = 0x00000000
 
 const (
 	LED    = PC18

src/machine/board_circuitplay_express.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_feather-m0.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_feather-m4-can.go

@@ -8,7 +8,7 @@ import (
 )
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_feather-m4.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_grandcentral-m4.go

@@ -245,7 +245,7 @@ const (
 
 // Other peripheral constants
 const (
-	RESET_MAGIC_VALUE = 0xF01669EF // Used to reset into bootloader
+	resetMagicValue = 0xF01669EF // Used to reset into bootloader
 )
 
 // USB CDC pins

src/machine/board_itsybitsy-m0.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_itsybitsy-m4.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_matrixportal-m4.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xF01669EF
+const resetMagicValue = 0xF01669EF
 
 // Digital pins
 const (

src/machine/board_metro-m4-airlift.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_p1am-100.go

@@ -7,7 +7,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0x07738135
+const resetMagicValue = 0x07738135
 
 // Note: On the P1AM-100, pins D8, D9, D10, A3, and A4 are used for
 // communication with the base controller.

src/machine/board_pybadge.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_pygamer.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_pyportal.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_qtpy.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_trinket.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/board_wioterminal.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 const (
 	ADC0 = A0

src/machine/board_xiao-ble.go

@@ -104,7 +104,7 @@ const (
 
 var (
 	usb_VID uint16 = 0x2886
-	usb_PID uint16 = 0x0045
+	usb_PID uint16 = 0x8045
 )
 
 var (

src/machine/board_xiao.go

@@ -4,7 +4,7 @@
 package machine
 
 // used to reset into bootloader
-const RESET_MAGIC_VALUE = 0xf01669ef
+const resetMagicValue = 0xf01669ef
 
 // GPIO Pins
 const (

src/machine/i2c.go

@@ -8,6 +8,8 @@ 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

src/machine/machine.go

@@ -18,6 +18,13 @@ 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.

src/machine/machine_atmega.go

@@ -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 = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 
 	// Activate internal pullups for twi.

src/machine/machine_atsamd21.go

@@ -10,7 +10,6 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
-	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -18,20 +17,20 @@ 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
@@ -150,7 +149,7 @@ 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
 		}
@@ -158,7 +157,7 @@ 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
 		}
@@ -382,7 +381,7 @@ 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
 }
 
@@ -677,7 +676,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 	if config.SDA == 0 && config.SCL == 0 {
 		config.SDA = SDA_PIN
@@ -1001,11 +1000,11 @@ 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.
@@ -1044,7 +1043,7 @@ 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)
@@ -1274,10 +1273,6 @@ 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.
@@ -1641,12 +1636,12 @@ 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
 }
@@ -1740,7 +1735,7 @@ func EnterBootloader() {
 
 	// Perform magic reset into bootloader, as mentioned in
 	// https://github.com/arduino/ArduinoCore-samd/issues/197
-	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = RESET_MAGIC_VALUE
+	*(*uint32)(unsafe.Pointer(uintptr(0x20007FFC))) = resetMagicValue
 
 	arm.SystemReset()
 }

src/machine/machine_atsamd21_usb.go

@@ -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_DM_PIN.Configure(PinConfig{Mode: pinCom})
-	USBCDC_DP_PIN.Configure(PinConfig{Mode: PinCom})
+	USBCDC_DP_PIN.Configure(PinConfig{Mode: pinCom})
 
 	// performs pad calibration from store fuses
 	handlePadCalibration()

src/machine/machine_atsamd21e18.go

@@ -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)

src/machine/machine_atsamd21g18.go

@@ -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)

src/machine/machine_atsamd51.go

@@ -10,7 +10,6 @@ package machine
 import (
 	"device/arm"
 	"device/sam"
-	"errors"
 	"runtime/interrupt"
 	"unsafe"
 )
@@ -22,30 +21,29 @@ 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
-	PinCAN           PinMode = 19
+
-	PinCAN0          PinMode = PinSDHC
+	// internal pin modes
-	PinCAN1          PinMode = PinCom
+	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
 )
 
 type PinChange uint8
@@ -339,7 +337,7 @@ 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
 		}
@@ -347,7 +345,7 @@ 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
 		}
@@ -581,65 +579,65 @@ 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)
@@ -815,7 +813,7 @@ 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.
@@ -1151,7 +1149,7 @@ const i2cTimeout = 1000
 func (i2c *I2C) Configure(config I2CConfig) error {
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 
 	// Use default I2C pins if not set.
@@ -1527,10 +1525,6 @@ 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.
@@ -1872,7 +1866,7 @@ 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) {
@@ -1884,12 +1878,12 @@ 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.
@@ -1980,7 +1974,7 @@ 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))) = RESET_MAGIC_VALUE
+	*(*uint32)(unsafe.Pointer(uintptr(0x20000000 + HSRAM_SIZE - 4))) = resetMagicValue
 
 	arm.SystemReset()
 }

src/machine/machine_atsamd51_usb.go

@@ -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_DM_PIN.Configure(PinConfig{Mode: pinCom})
-	USBCDC_DP_PIN.Configure(PinConfig{Mode: PinCom})
+	USBCDC_DP_PIN.Configure(PinConfig{Mode: pinCom})
 
 	// performs pad calibration from store fuses
 	handlePadCalibration()

src/machine/machine_atsame5x_can.go

@@ -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})

src/machine/machine_esp32c3.go

@@ -59,12 +59,9 @@ type PinChange uint8
 
 // Pin change interrupt constants for SetInterrupt.
 const (
-	PinNoInterrupt PinChange = iota
+	PinRising PinChange = iota + 1
-	PinRising
 	PinFalling
 	PinToggle
-	PinLowLevel
-	PinHighLevel
 )
 
 // Configure this pin with the given configuration.
@@ -190,7 +187,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) (err error) {
 		return ErrInvalidInputPin
 	}
 
-	if callback == nil || change == PinNoInterrupt {
+	if callback == nil {
 		// Disable this pin interrupt
 		p.pin().ClearBits(esp.GPIO_PIN_PIN_INT_TYPE_Msk | esp.GPIO_PIN_PIN_INT_ENA_Msk)
 
@@ -264,15 +261,6 @@ 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

src/machine/machine_fe310.go

@@ -18,9 +18,11 @@ func CPUFrequency() uint32 {
 const (
 	PinInput PinMode = iota
 	PinOutput
-	PinPWM
+
-	PinSPI
+	// internal pin modes
-	PinI2C = PinSPI
+	pinPWM
+	pinSPI
+	pinI2C = pinSPI
 )
 
 // Configure this pin with the given configuration.
@@ -29,10 +31,10 @@ 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))
 	}
@@ -145,9 +147,9 @@ func (spi SPI) Configure(config SPIConfig) error {
 	}
 
 	// enable pins for SPI
-	config.SCK.Configure(PinConfig{Mode: PinSPI})
+	config.SCK.Configure(PinConfig{Mode: pinSPI})
-	config.SDO.Configure(PinConfig{Mode: PinSPI})
+	config.SDO.Configure(PinConfig{Mode: pinSPI})
-	config.SDI.Configure(PinConfig{Mode: PinSPI})
+	config.SDI.Configure(PinConfig{Mode: pinSPI})
 
 	// set default frequency
 	if config.Frequency == 0 {
@@ -231,7 +233,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 	var i2cClockFrequency uint32 = 32000000
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 
 	if config.SDA == 0 && config.SCL == 0 {
@@ -251,8 +253,8 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 	// enable controller
 	i2c.Bus.CTR.SetBits(sifive.I2C_CTR_EN)
 
-	config.SDA.Configure(PinConfig{Mode: PinI2C})
+	config.SDA.Configure(PinConfig{Mode: pinI2C})
-	config.SCL.Configure(PinConfig{Mode: PinI2C})
+	config.SCL.Configure(PinConfig{Mode: pinI2C})
 
 	return nil
 }

src/machine/machine_k210.go

@@ -23,11 +23,17 @@ type PinChange uint8
 // Pin modes.
 const (
 	PinInput PinMode = iota
-	PinInputPullUp
+	PinInputPullup
-	PinInputPullDown
+	PinInputPulldown
 	PinOutput
 )
 
+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
+)
+
 // FPIOA internal pull resistors.
 const (
 	fpioaPullNone fpioaPullMode = iota
@@ -89,10 +95,10 @@ 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:
@@ -517,7 +523,7 @@ type I2CConfig struct {
 func (i2c *I2C) Configure(config I2CConfig) error {
 
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 
 	if config.SDA == 0 && config.SCL == 0 {

src/machine/machine_mimxrt1062.go

@@ -21,36 +21,40 @@ func CPUFrequency() uint32 {
 const (
 	// GPIO
 	PinInput PinMode = iota
-	PinInputPullUp
+	PinInputPullup
-	PinInputPullDown
+	PinInputPulldown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable
 
 	// ADC
-	PinInputAnalog
+	pinInputAnalog
 
 	// UART
-	PinModeUARTTX
+	pinModeUARTTX
-	PinModeUARTRX
+	pinModeUARTRX
 
 	// SPI
-	PinModeSPISDI
+	pinModeSPISDI
-	PinModeSPISDO
+	pinModeSPISDO
-	PinModeSPICLK
+	pinModeSPICLK
-	PinModeSPICS
+	pinModeSPICS
 
 	// I2C
-	PinModeI2CSDA
+	pinModeI2CSDA
-	PinModeI2CSCL
+	pinModeI2CSCL
+)
+
+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
 )
 
 type PinChange uint8
 
 const (
-	PinLow PinChange = iota
+	PinRising PinChange = iota + 2
-	PinHigh
-	PinRising
 	PinFalling
 	PinToggle
 )
@@ -259,11 +263,11 @@ 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)
 
@@ -279,29 +283,29 @@ 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))
 	}
 
@@ -387,7 +391,7 @@ func (p Pin) SetInterrupt(change PinChange, callback func(Pin)) error {
 	mask := p.getMask()
 	if nil != callback {
 		switch change {
-		case PinLow, PinHigh, PinRising, PinFalling:
+		case PinRising, PinFalling:
 			gpio.EDGE_SEL.ClearBits(mask)
 			var reg *volatile.Register32
 			var pos uint8
@@ -746,7 +750,7 @@ 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 {
@@ -755,7 +759,7 @@ 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
@@ -763,7 +767,7 @@ 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 {
@@ -772,7 +776,7 @@ 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
@@ -790,7 +794,7 @@ 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
@@ -808,7 +812,7 @@ 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
@@ -826,7 +830,7 @@ 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
@@ -844,7 +848,7 @@ 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
@@ -862,7 +866,7 @@ 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
@@ -898,7 +902,7 @@ 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 {

src/machine/machine_mimxrt1062_i2c.go

@@ -10,15 +10,6 @@ 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")
@@ -165,8 +156,8 @@ func (i2c *I2C) Configure(config I2CConfig) {
 	sda, scl := i2c.setPins(config)
 
 	// configure the mux and pad control registers
-	sda.Configure(PinConfig{Mode: PinModeI2CSDA})
+	sda.Configure(PinConfig{Mode: pinModeI2CSDA})
-	scl.Configure(PinConfig{Mode: PinModeI2CSCL})
+	scl.Configure(PinConfig{Mode: pinModeI2CSCL})
 
 	// configure the mux input selector
 	i2c.muxSDA.connect()
@@ -174,7 +165,7 @@ func (i2c *I2C) Configure(config I2CConfig) {
 
 	freq := config.Frequency
 	if 0 == freq {
-		freq = TWI_FREQ_DEFAULT
+		freq = 100 * KHz
 	}
 
 	// reset clock and registers, and enable LPI2C module interface
@@ -305,7 +296,7 @@ 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 = (TWI_FREQ_BUS/(2^pre))/(CLKLO+1 + CLKHI+1 + FLOOR((2+FILTSCL)/(2^pre)))
+	// baud rate = (24MHz/(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 {
@@ -314,9 +305,9 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		for clkHi := uint32(1); clkHi < 32; clkHi++ {
 			var absError, rate uint32
 			if clkHi == 1 {
-				rate = (TWI_FREQ_BUS / pre) / (1 + 3 + 2 + 2/pre)
+				rate = (24 * MHz / pre) / (1 + 3 + 2 + 2/pre)
 			} else {
-				rate = (TWI_FREQ_BUS / pre) / (3*clkHi + 2 + 2/pre)
+				rate = (24 * MHz / pre) / (3*clkHi + 2 + 2/pre)
 			}
 			if freq > rate {
 				absError = freq - rate
@@ -370,15 +361,15 @@ func (i2c *I2C) setFrequency(freq uint32) {
 		mcfgr2, mcfgr3 uint32
 	)
 	const i2cClockStretchTimeout = 15000 // microseconds
-	if freq >= TWI_FREQ_5MHZ {
+	if freq >= 5*MHz {
 		// I2C UltraFastMode 5 MHz
 		mcfgr2 = 0 // disable glitch filters and timeout for UltraFastMode
 		mcfgr3 = 0 //
-	} else if freq >= TWI_FREQ_1MHZ {
+	} else if freq >= 1*MHz {
 		// I2C FastModePlus 1 MHz
 		mcfgr2 = filtsda(1) | filtscl(1) | busidle(2400) // 100us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)
-	} else if freq >= TWI_FREQ_400KHZ {
+	} else if freq >= 400*KHz {
 		// I2C FastMode 400 kHz
 		mcfgr2 = filtsda(2) | filtscl(2) | busidle(3600) // 150us timeout
 		mcfgr3 = pinlow(i2cClockStretchTimeout*24/256 + 1)

src/machine/machine_mimxrt1062_spi.go

@@ -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.sdi.Configure(PinConfig{Mode: pinModeSPISDI})
-	spi.sdo.Configure(PinConfig{Mode: PinModeSPISDO})
+	spi.sdo.Configure(PinConfig{Mode: pinModeSPISDO})
-	spi.sck.Configure(PinConfig{Mode: PinModeSPICLK})
+	spi.sck.Configure(PinConfig{Mode: pinModeSPICLK})
-	spi.cs.Configure(PinConfig{Mode: PinModeSPICS})
+	spi.cs.Configure(PinConfig{Mode: pinModeSPICS})
 
 	// configure the mux input selector
 	spi.muxSDI.connect()

src/machine/machine_mimxrt1062_uart.go

@@ -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.rx.Configure(PinConfig{Mode: pinModeUARTRX})
-	uart.tx.Configure(PinConfig{Mode: PinModeUARTTX})
+	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.rx.Configure(PinConfig{Mode: PinInputPullup})
-		uart.tx.Configure(PinConfig{Mode: PinInputPullUp})
+		uart.tx.Configure(PinConfig{Mode: PinInputPullup})
 	}
 	uart.configured = false
 }

src/machine/machine_nrf.go

@@ -5,15 +5,10 @@ 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 (
@@ -230,7 +225,7 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 
 	// Default I2C bus speed is 100 kHz.
 	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 	// Default I2C pins if not set.
 	if config.SDA == 0 && config.SCL == 0 {
@@ -253,7 +248,7 @@ 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 == TWI_FREQ_400KHZ {
+	if config.Frequency >= 400*KHz {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K400)
 	} else {
 		i2c.Bus.FREQUENCY.Set(nrf.TWI_FREQUENCY_FREQUENCY_K100)
@@ -350,3 +345,41 @@ 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
+}

src/machine/machine_nrf52840_enter_bootloader.go

@@ -9,16 +9,16 @@ import (
 )
 
 const (
-	DFU_MAGIC_SERIAL_ONLY_RESET = 0x4e
+	dfuMagicSerialOnlyReset = 0x4e
-	DFU_MAGIC_UF2_RESET         = 0x57
+	dfuMagicUF2Reset        = 0x57
-	DFU_MAGIC_OTA_RESET         = 0xA8
+	dfuMagicOTAReset        = 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(DFU_MAGIC_SERIAL_ONLY_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicSerialOnlyReset)
 	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(DFU_MAGIC_UF2_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicUF2Reset)
 	arm.SystemReset()
 }
 
@@ -34,6 +34,6 @@ func EnterUF2Bootloader() {
 // flashed via an OTA update
 func EnterOTABootloader() {
 	arm.DisableInterrupts()
-	nrf.POWER.GPREGRET.Set(DFU_MAGIC_OTA_RESET)
+	nrf.POWER.GPREGRET.Set(dfuMagicOTAReset)
 	arm.SystemReset()
 }

src/machine/machine_nrf52840_rng.go

@@ -1,60 +0,0 @@
-//go:build nrf52840
-// +build nrf52840
-
-package machine
-
-import (
-	"device/nrf"
-)
-
-// Implementation based on Nordic Semiconductor's nRF52840 documentation version 1.7 found here:
-// https://infocenter.nordicsemi.com/pdf/nRF52840_PS_v1.7.pdf
-
-// SetRNGBiasCorrection configures the RNG peripheral's bias correction mechanism. Note that when
-// bias correction is enabled, the peripheral is slower to produce random values.
-func SetRNGBiasCorrection(enabled bool) {
-	var val uint32
-	if enabled {
-		val = nrf.RNG_CONFIG_DERCEN_Enabled
-	}
-	nrf.RNG.SetCONFIG_DERCEN(val)
-}
-
-// RNGBiasCorrectionEnabled determines whether the RNG peripheral's bias correction mechanism is
-// enabled or not.
-func RNGBiasCorrectionEnabled() bool {
-	return nrf.RNG.GetCONFIG_DERCEN() == nrf.RNG_CONFIG_DERCEN_Enabled
-}
-
-// StartRNG starts the RNG peripheral core. This is automatically called by GetRNG, but can be
-// manually called for interacting with the RNG peripheral directly.
-func StartRNG() {
-	nrf.RNG.SetTASKS_START(nrf.RNG_TASKS_START_TASKS_START_Trigger)
-}
-
-// StopRNG stops the RNG peripheral core. This is not called automatically. It may make sense to
-// manually disable RNG peripheral for power conservation.
-func StopRNG() {
-	nrf.RNG.SetTASKS_STOP(nrf.RNG_TASKS_STOP_TASKS_STOP_Trigger)
-}
-
-// 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.
-	StartRNG()
-
-	// 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.GetEVENTS_VALRDY() == nrf.RNG_EVENTS_VALRDY_EVENTS_VALRDY_NotGenerated {
-		}
-		// 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.SetEVENTS_VALRDY(nrf.RNG_EVENTS_VALRDY_EVENTS_VALRDY_NotGenerated)
-	}
-
-	return ret, nil
-}

src/machine/machine_nxpmk66f18.go

@@ -42,13 +42,19 @@ const deviceName = nxp.Device
 
 const (
 	PinInput PinMode = iota
-	PinInputPullUp
+	PinInputPullup
-	PinInputPullDown
+	PinInputPulldown
 	PinOutput
 	PinOutputOpenDrain
 	PinDisable
 )
 
+// Deprecated: use PinInputPullup and PinInputPulldown instead.
+const (
+	PinInputPullUp   = PinInputPullup
+	PinInputPullDown = PinInputPulldown
+)
+
 const (
 	PA00 Pin = iota
 	PA01
@@ -223,11 +229,11 @@ 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)
 

src/machine/machine_nxpmk66f18_uart.go

@@ -203,8 +203,8 @@ func (u *UART) Disable() {
 	u.C2.Set(0)
 
 	// reconfigure pin
-	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullUp})
+	u.DefaultRX.Configure(PinConfig{Mode: PinInputPullup})
-	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullUp})
+	u.DefaultTX.Configure(PinConfig{Mode: PinInputPullup})
 
 	// clear flags
 	u.S1.Get()

src/machine/machine_rp2040_adc.go

@@ -17,8 +17,8 @@ const (
 	adc0_CH ADCChannel = iota
 	adc1_CH
 	adc2_CH
-	adc3_CH         // Note: GPIO29 not broken out on pico board
+	adc3_CH       // Note: GPIO29 not broken out on pico board
-	ADC_TEMP_SENSOR // Internal temperature sensor channel
+	adcTempSensor // Internal temperature sensor channel
 )
 
 // Used to serialise ADC sampling
@@ -75,19 +75,17 @@ func (a ADC) GetADCChannel() (c ADCChannel, err error) {
 	return c, err
 }
 
-// Configure sets the channel's associated pin to analog input mode or powers on the temperature sensor for ADC_TEMP_SENSOR.
+// Configure sets the channel's associated pin to analog input mode.
 // 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
 	}
-	if p, err := c.Pin(); err == nil {
+	p, err := c.Pin()
-		p.Configure(PinConfig{Mode: PinAnalog})
+	if err != nil {
-	}
+		return err
-	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
 }
 
@@ -112,13 +110,16 @@ func (c ADCChannel) getVoltage() uint32 {
 }
 
 // ReadTemperature does a one-shot sample of the internal temperature sensor and returns a milli-celsius reading.
-// Only works on the ADC_TEMP_SENSOR channel. aka AINSEL=4. Other channels will return 0
+func ReadTemperature() (millicelsius int32) {
-func (c ADCChannel) ReadTemperature() (millicelsius uint32) {
+	if rp.ADC.CS.Get()&rp.ADC_CS_EN == 0 {
-	if c != ADC_TEMP_SENSOR {
+		InitADC()
-		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 - (c.getVoltage()-706<<16)*581) >> 16
+	return (27000<<16 - (int32(adcTempSensor.getVoltage())-706<<16)*581) >> 16
 }
 
 // waitForReady spins waiting for the ADC peripheral to become ready.

src/machine/machine_rp2040_clocks.go

@@ -10,11 +10,6 @@ import (
 	"unsafe"
 )
 
-const (
-	KHz = 1000
-	MHz = 1000000
-)
-
 func CPUFrequency() uint32 {
 	return 125 * MHz
 }

src/machine/machine_rp2040_gpio.go

@@ -81,11 +81,13 @@ const (
 	PinInput
 	PinInputPulldown
 	PinInputPullup
-	PinAnalog
+
-	PinUART
+	// internal pin modes
-	PinPWM
+	pinAnalog
-	PinI2C
+	pinUART
-	PinSPI
+	pinPWM
+	pinI2C
+	pinSPI
 )
 
 func (p Pin) PortMaskSet() (*uint32, uint32) {
@@ -188,20 +190,20 @@ 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)
 	}
 }
@@ -226,12 +228,8 @@ 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
+	PinFalling PinChange = 4 << iota
 	// Edge rising
 	PinRising
 )

src/machine/machine_rp2040_i2c.go

@@ -105,8 +105,8 @@ func (i2c *I2C) Configure(config I2CConfig) error {
 	if config.Frequency == 0 {
 		config.Frequency = defaultBaud
 	}
-	config.SDA.Configure(PinConfig{PinI2C})
+	config.SDA.Configure(PinConfig{pinI2C})
-	config.SCL.Configure(PinConfig{PinI2C})
+	config.SCL.Configure(PinConfig{pinI2C})
 	return i2c.init(config)
 }
 

src/machine/machine_rp2040_pwm.go

@@ -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
 }
 

src/machine/machine_rp2040_rng.go

@@ -13,6 +13,10 @@ import (
 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++ {

src/machine/machine_rp2040_spi.go

@@ -38,10 +38,9 @@ type SPIConfig struct {
 }
 
 var (
-	ErrLSBNotSupported    = errors.New("SPI LSB unsupported on PL022")
+	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")
-	ErrSPITimeout         = errors.New("SPI timeout")
+	ErrSPIBaud         = errors.New("SPI baud too low or above 66.5Mhz")
-	ErrSPIBaud            = errors.New("SPI baud too low or above 66.5Mhz")
 )
 
 type SPI struct {

src/machine/machine_rp2040_uart.go

@@ -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.TX.Configure(PinConfig{Mode: pinUART})
-	config.RX.Configure(PinConfig{Mode: PinUART})
+	config.RX.Configure(PinConfig{Mode: pinUART})
 
 	// Enable RX IRQ.
 	uart.Interrupt.SetPriority(0x80)

src/machine/machine_stm32_adc_f1.go

@@ -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()

src/machine/machine_stm32_adc_f4.go

@@ -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()

src/machine/machine_stm32_i2c_reva.go

@@ -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 = TWI_FREQ_100KHZ
+		config.Frequency = 100 * KHz
 	}
 
 	// configure I2C input clock

src/machine/machine_stm32_i2c_revb.go

@@ -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.SCL.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSCL}, i2c.AltFuncSelector)
-	config.SDA.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSDA}, i2c.AltFuncSelector)
+	config.SDA.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSDA}, i2c.AltFuncSelector)
 }
 
 func (i2c *I2C) controllerTransmit(addr uint16, w []byte) error {

src/machine/machine_stm32_moder_gpio.go

@@ -14,29 +14,28 @@ import (
 const (
 	// Mode Flag
 	PinOutput        PinMode = 0
-	PinInput         PinMode = PinInputFloating
+	PinInput         PinMode = 1
-	PinInputFloating PinMode = 1
 	PinInputPulldown PinMode = 2
 	PinInputPullup   PinMode = 3
 
 	// for UART
-	PinModeUARTTX PinMode = 4
+	pinModeUARTTX PinMode = 4
-	PinModeUARTRX PinMode = 5
+	pinModeUARTRX PinMode = 5
 
 	// for I2C
-	PinModeI2CSCL PinMode = 6
+	pinModeI2CSCL PinMode = 6
-	PinModeI2CSDA PinMode = 7
+	pinModeI2CSDA PinMode = 7
 
 	// for SPI
-	PinModeSPICLK PinMode = 8
+	pinModeSPICLK PinMode = 8
-	PinModeSPISDO PinMode = 9
+	pinModeSPISDO PinMode = 9
-	PinModeSPISDI PinMode = 10
+	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
@@ -83,7 +82,7 @@ func (p Pin) ConfigureAltFunc(config PinConfig, altFunc uint8) {
 	switch config.Mode {
 
 	// GPIO
-	case PinInputFloating:
+	case PinInput:
 		port.MODER.ReplaceBits(gpioModeInput, gpioModeMask, pos)
 		port.PUPDR.ReplaceBits(gpioPullFloating, gpioPullMask, pos)
 	case PinInputPulldown:
@@ -97,24 +96,24 @@ 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)
@@ -122,31 +121,31 @@ 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)
 	}
 }

src/machine/machine_stm32_tim.go

@@ -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
 			}
 		}

src/machine/machine_stm32_tim_moder.go

@@ -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)
 }

src/machine/machine_stm32f103.go

@@ -29,20 +29,20 @@ const (
 	PinOutput50MHz PinMode = 3 // Output mode, max speed 50MHz
 	PinOutput      PinMode = PinOutput2MHz
 
-	PinInputModeAnalog     PinMode = 0  // Input analog mode
+	pinInputModeAnalog     PinMode = 0  // Input analog mode
-	PinInputModeFloating   PinMode = 4  // Input floating mode
+	pinInputModeFloating   PinMode = 4  // Input floating mode
-	PinInputModePullUpDown PinMode = 8  // Input pull up/down mode
+	pinInputModePullUpDown PinMode = 8  // Input pull up/down mode
-	PinInputModeReserved   PinMode = 12 // Input mode (reserved)
+	pinInputModeReserved   PinMode = 12 // Input mode (reserved)
 
-	PinOutputModeGPPushPull   PinMode = 0  // Output mode general purpose push/pull
+	pinOutputModeGPPushPull   PinMode = 0  // Output mode general purpose push/pull
-	PinOutputModeGPOpenDrain  PinMode = 4  // Output mode general purpose open drain
+	pinOutputModeGPOpenDrain  PinMode = 4  // Output mode general purpose open drain
-	PinOutputModeAltPushPull  PinMode = 8  // Output mode alt. purpose push/pull
+	pinOutputModeAltPushPull  PinMode = 8  // Output mode alt. purpose push/pull
-	PinOutputModeAltOpenDrain PinMode = 12 // Output mode alt. purpose open drain
+	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
+	PinInputPulldown PinMode = pinInputModePullUpDown
-	PinInputPullup   PinMode = PinInputModePullUpDown | 0x10
+	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.TX.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.RX.Configure(PinConfig{Mode: PinInputModeFloating})
+	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.SCK.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.SDO.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
+	config.SDO.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltPushPull})
-	config.SDI.Configure(PinConfig{Mode: PinInputModeFloating})
+	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.SDA.Configure(PinConfig{Mode: PinOutput50MHz + pinOutputModeAltOpenDrain})
-	config.SCL.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() {

src/machine/machine_stm32f4.go

@@ -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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	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.SCK.ConfigureAltFunc(PinConfig{Mode: pinModeSPICLK}, spi.AltFuncSelector)
-	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
+	config.SDO.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDO}, spi.AltFuncSelector)
-	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, 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.SCL.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSCL}, i2c.AltFuncSelector)
-	config.SDA.ConfigureAltFunc(PinConfig{Mode: PinModeI2CSDA}, i2c.AltFuncSelector)
+	config.SDA.ConfigureAltFunc(PinConfig{Mode: pinModeI2CSDA}, i2c.AltFuncSelector)
 }
 
 func (i2c *I2C) getFreqRange(config I2CConfig) uint32 {

src/machine/machine_stm32f7x2.go

@@ -24,8 +24,8 @@ const APB2_TIM_FREQ = 216e6 // 216MHz
 // Configure the UART.
 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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
 }
 
 // UART baudrate calc based on the bus and clockspeed

src/machine/machine_stm32l0.go

@@ -195,8 +195,8 @@ func (p Pin) registerInterrupt() interrupt.Interrupt {
 // Configure the UART.
 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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
 }
 
 // UART baudrate calc based on the bus and clockspeed
@@ -289,9 +289,9 @@ func (spi SPI) getBaudRate(config SPIConfig) uint32 {
 
 // Configure SPI pins for input output and clock
 func (spi SPI) configurePins(config SPIConfig) {
-	config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
+	config.SCK.ConfigureAltFunc(PinConfig{Mode: pinModeSPICLK}, spi.AltFuncSelector)
-	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
+	config.SDO.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDO}, spi.AltFuncSelector)
-	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, spi.AltFuncSelector)
+	config.SDI.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDI}, spi.AltFuncSelector)
 }
 
 //---------- I2C related types and code

src/machine/machine_stm32l4.go

@@ -280,8 +280,8 @@ func (p Pin) registerInterrupt() interrupt.Interrupt {
 // Configure the UART.
 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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
 }
 
 // UART baudrate calc based on the bus and clockspeed
@@ -357,9 +357,9 @@ func (spi SPI) getBaudRate(config SPIConfig) uint32 {
 
 // Configure SPI pins for input output and clock
 func (spi SPI) configurePins(config SPIConfig) {
-	config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
+	config.SCK.ConfigureAltFunc(PinConfig{Mode: pinModeSPICLK}, spi.AltFuncSelector)
-	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
+	config.SDO.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDO}, spi.AltFuncSelector)
-	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, spi.AltFuncSelector)
+	config.SDI.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDI}, spi.AltFuncSelector)
 }
 
 //---------- Timer related code

src/machine/machine_stm32l5x2.go

@@ -29,8 +29,8 @@ 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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
 }
 
 // UART baudrate calc based on the bus and clockspeed

src/machine/machine_stm32wlx.go

@@ -239,9 +239,9 @@ func (spi SPI) config8Bits() {
 }
 
 func (spi SPI) configurePins(config SPIConfig) {
-	config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
+	config.SCK.ConfigureAltFunc(PinConfig{Mode: pinModeSPICLK}, spi.AltFuncSelector)
-	config.SDO.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDO}, spi.AltFuncSelector)
+	config.SDO.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDO}, spi.AltFuncSelector)
-	config.SDI.ConfigureAltFunc(PinConfig{Mode: PinModeSPISDI}, spi.AltFuncSelector)
+	config.SDI.ConfigureAltFunc(PinConfig{Mode: pinModeSPISDI}, spi.AltFuncSelector)
 }
 
 func (spi SPI) getBaudRate(config SPIConfig) uint32 {
@@ -298,8 +298,8 @@ func (i2c *I2C) getFreqRange() uint32 {
 // Configure the UART.
 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.TX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTTX}, uart.TxAltFuncSelector)
-	config.RX.ConfigureAltFunc(PinConfig{Mode: PinModeUARTRX}, uart.RxAltFuncSelector)
+	config.RX.ConfigureAltFunc(PinConfig{Mode: pinModeUARTRX}, uart.RxAltFuncSelector)
 }
 
 // UART baudrate calc based on the bus and clockspeed

src/machine/spi.go

@@ -1,5 +1,5 @@
-//go:build !baremetal || (stm32 && !stm32f7x2 && !stm32l5x2) || fe310 || k210 || (nxp && !mk66f18) || atmega
+//go:build !baremetal || atmega || esp32 || fe310 || k210 || nrf || (nxp && !mk66f18) || rp2040 || sam || (stm32 && !stm32f7x2 && !stm32l5x2)
-// +build !baremetal stm32,!stm32f7x2,!stm32l5x2 fe310 k210 nxp,!mk66f18 atmega
+// +build !baremetal atmega esp32 fe310 k210 nrf nxp,!mk66f18 rp2040 sam stm32,!stm32f7x2,!stm32l5x2
 
 package machine
 
@@ -17,58 +17,3 @@ var (
 	ErrTxInvalidSliceSize      = errors.New("SPI write and read slices must be same size")
 	errSPIInvalidMachineConfig = errors.New("SPI port was not configured properly by the machine")
 )
-
-// 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.
-//
-// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
-// Note that the tx and rx buffers must be the same size:
-//
-//	spi.Tx(tx, rx)
-//
-// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
-// until all the bytes in the command packet have been received:
-//
-//	spi.Tx(tx, nil)
-//
-// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
-//
-//	spi.Tx(nil, rx)
-func (spi SPI) Tx(w, r []byte) error {
-	var err error
-
-	switch {
-	case w == nil:
-		// read only, so write zero and read a result.
-		for i := range r {
-			r[i], err = spi.Transfer(0)
-			if err != nil {
-				return err
-			}
-		}
-	case r == nil:
-		// write only
-		for _, b := range w {
-			_, err = spi.Transfer(b)
-			if err != nil {
-				return err
-			}
-		}
-
-	default:
-		// write/read
-		if len(w) != len(r) {
-			return ErrTxInvalidSliceSize
-		}
-
-		for i, b := range w {
-			r[i], err = spi.Transfer(b)
-			if err != nil {
-				return err
-			}
-		}
-	}
-
-	return nil
-}

src/machine/spi_tx.go

@@ -0,0 +1,62 @@
+//go:build !baremetal || atmega || fe310 || k210 || (nxp && !mk66f18) || (stm32 && !stm32f7x2 && !stm32l5x2)
+// +build !baremetal atmega fe310 k210 nxp,!mk66f18 stm32,!stm32f7x2,!stm32l5x2
+
+// This file implements the SPI Tx function for targets that don't have a custom
+// (faster) implementation for it.
+
+package machine
+
+// 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.
+//
+// This form sends the bytes in tx buffer, putting the resulting bytes read into the rx buffer.
+// Note that the tx and rx buffers must be the same size:
+//
+//	spi.Tx(tx, rx)
+//
+// This form sends the tx buffer, ignoring the result. Useful for sending "commands" that return zeros
+// until all the bytes in the command packet have been received:
+//
+//	spi.Tx(tx, nil)
+//
+// This form sends zeros, putting the result into the rx buffer. Good for reading a "result packet":
+//
+//	spi.Tx(nil, rx)
+func (spi SPI) Tx(w, r []byte) error {
+	var err error
+
+	switch {
+	case w == nil:
+		// read only, so write zero and read a result.
+		for i := range r {
+			r[i], err = spi.Transfer(0)
+			if err != nil {
+				return err
+			}
+		}
+	case r == nil:
+		// write only
+		for _, b := range w {
+			_, err = spi.Transfer(b)
+			if err != nil {
+				return err
+			}
+		}
+
+	default:
+		// write/read
+		if len(w) != len(r) {
+			return ErrTxInvalidSliceSize
+		}
+
+		for i, b := range w {
+			r[i], err = spi.Transfer(b)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}

src/machine/uart.go

@@ -8,20 +8,20 @@ import "errors"
 var errUARTBufferEmpty = errors.New("UART buffer empty")
 
 // UARTParity is the parity setting to be used for UART communication.
-type UARTParity int
+type UARTParity uint8
 
 const (
 	// ParityNone means to not use any parity checking. This is
 	// the most common setting.
-	ParityNone UARTParity = 0
+	ParityNone UARTParity = iota
 
 	// ParityEven means to expect that the total number of 1 bits sent
 	// should be an even number.
-	ParityEven UARTParity = 1
+	ParityEven
 
 	// ParityOdd means to expect that the total number of 1 bits sent
 	// should be an odd number.
-	ParityOdd UARTParity = 2
+	ParityOdd
 )
 
 // To implement the UART interface for a board, you must declare a concrete type as follows:

src/runtime/arch_tinygowasm.go

@@ -20,21 +20,46 @@ var heapStartSymbol [0]byte
 //go:extern __global_base
 var globalsStartSymbol [0]byte
 
+const (
+	// wasmMemoryIndex is always zero until the multi-memory feature is used.
+	//
+	// See https://github.com/WebAssembly/multi-memory
+	wasmMemoryIndex = 0
+
+	// wasmPageSize is the size of a page in WebAssembly's 32-bit memory. This
+	// is also its only unit of change.
+	//
+	// See https://www.w3.org/TR/wasm-core-1/#page-size
+	wasmPageSize = 64 * 1024
+)
+
+// wasm_memory_size invokes the "memory.size" instruction, which returns the
+// current size to the memory at the given index (always wasmMemoryIndex), in
+// pages.
+//
 //export llvm.wasm.memory.size.i32
 func wasm_memory_size(index int32) int32
 
+// wasm_memory_grow invokes the "memory.grow" instruction, which attempts to
+// increase the size of the memory at the given index (always wasmMemoryIndex),
+// by the delta (in pages). This returns the previous size on success of -1 on
+// failure.
+//
 //export llvm.wasm.memory.grow.i32
 func wasm_memory_grow(index int32, delta int32) int32
 
 var (
-	heapStart    = uintptr(unsafe.Pointer(&heapStartSymbol))
+	// heapStart is the current memory offset which starts the heap. The heap
-	heapEnd      = uintptr(wasm_memory_size(0) * wasmPageSize)
+	// extends from this offset until heapEnd (exclusive).
+	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
+
+	// heapEnd is the current memory length in bytes.
+	heapEnd = uintptr(wasm_memory_size(wasmMemoryIndex) * wasmPageSize)
+
 	globalsStart = uintptr(unsafe.Pointer(&globalsStartSymbol))
 	globalsEnd   = uintptr(unsafe.Pointer(&heapStartSymbol))
 )
 
-const wasmPageSize = 64 * 1024
-
 func align(ptr uintptr) uintptr {
 	// Align to 16, which is the alignment of max_align_t:
 	// https://godbolt.org/z/dYqTsWrGq
@@ -48,14 +73,14 @@ func getCurrentStackPointer() uintptr
 // otherwise.
 func growHeap() bool {
 	// Grow memory by the available size, which means the heap size is doubled.
-	memorySize := wasm_memory_size(0)
+	memorySize := wasm_memory_size(wasmMemoryIndex)
-	result := wasm_memory_grow(0, memorySize)
+	result := wasm_memory_grow(wasmMemoryIndex, memorySize)
 	if result == -1 {
 		// Grow failed.
 		return false
 	}
 
-	setHeapEnd(uintptr(wasm_memory_size(0) * wasmPageSize))
+	setHeapEnd(uintptr(wasm_memory_size(wasmMemoryIndex) * wasmPageSize))
 
 	// Heap has grown successfully.
 	return true
@@ -68,7 +93,6 @@ func growHeap() bool {
 var allocs = make(map[uintptr][]byte)
 
 //export malloc
-//go:wasm-module
 func libc_malloc(size uintptr) unsafe.Pointer {
 	buf := make([]byte, size)
 	ptr := unsafe.Pointer(&buf[0])
@@ -77,7 +101,6 @@ func libc_malloc(size uintptr) unsafe.Pointer {
 }
 
 //export free
-//go:wasm-module
 func libc_free(ptr unsafe.Pointer) {
 	if ptr == nil {
 		return
@@ -90,14 +113,12 @@ func libc_free(ptr unsafe.Pointer) {
 }
 
 //export calloc
-//go:wasm-module
 func libc_calloc(nmemb, size uintptr) unsafe.Pointer {
 	// No difference between calloc and malloc.
 	return libc_malloc(nmemb * size)
 }
 
 //export realloc
-//go:wasm-module
 func libc_realloc(oldPtr unsafe.Pointer, size uintptr) unsafe.Pointer {
 	// It's hard to optimize this to expand the current buffer with our GC, but
 	// it is theoretically possible. For now, just always allocate fresh.