ws2812: add SPI based implementation

This is useful because it allows using the WS2812 driver on platforms
without bitbanged WS2812 support and it may be the only option if
disabling interrupts is impossible or impractical.

.circleci/config.yml

@@ -12,6 +12,9 @@ jobs:
       - run:
           name: "Enforce Go Formatted Code"
           command: make fmt-check
+      - run:
+          name: "Run unit tests"
+          command: make unit-test
       - run:
           name: "Run build and smoke tests"
           command: make smoke-test

Makefile

@@ -132,6 +132,8 @@ smoke-test:
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/ws2812
 	@md5sum ./build/test.hex
 ifneq ($(AVR), 0)
+	tinygo build -size short -o ./build/test.hex -target=arduino   ./examples/ws2812
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=digispark ./examples/ws2812
 	@md5sum ./build/test.hex
 endif
@@ -158,4 +160,13 @@ endif
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/lis2mdl/main.go
 	@md5sum ./build/test.hex
 
-test: clean fmt-check smoke-test
+DRIVERS = $(wildcard */)
+NOTESTS = build examples flash semihosting pcd8544 shiftregister st7789 microphone mcp3008 gps microbitmatrix \
+		hcsr04 ssd1331 ws2812 thermistor apa102 easystepper ssd1351 ili9341 wifinina shifter hub75 \
+		hd44780 buzzer ssd1306 espat l9110x st7735 bmi160 l293x
+TESTS = $(filter-out $(addsuffix /%,$(NOTESTS)),$(DRIVERS))
+
+unit-test:
+	@go test -v $(addprefix ./,$(TESTS)) 
+
+test: clean fmt-check unit-test smoke-test

apa102/apa102.go

@@ -6,6 +6,8 @@ package apa102 // import "tinygo.org/x/drivers/apa102"
 import (
 	"image/color"
 	"machine"
+
+	"tinygo.org/x/drivers"
 )
 
 const (
@@ -23,20 +25,12 @@ var startFrame = []byte{0x00, 0x00, 0x00, 0x00}
 
 // Device wraps APA102 SPI LEDs.
 type Device struct {
-	bus   SPI
+	bus   drivers.SPI
 	Order int
 }
 
-// The SPI interface specifies the minimum functionality that a bus
-// implementation needs to provide for use by the APA102 driver.  Hardware
-// SPI from the TinyGo "machine" package implements this already.
-type SPI interface {
-	Tx(w, r []byte) error
-	Transfer(b byte) (byte, error)
-}
-
 // New returns a new APA102 driver. Pass in a fully configured SPI bus.
-func New(b SPI) Device {
+func New(b drivers.SPI) Device {
 	return Device{bus: b, Order: BGR}
 }
 

bmi160/bmi160.go

@@ -1,8 +1,11 @@
 package bmi160
 
-import "machine"
+import (
+	"machine"
+	"time"
 
-import "time"
+	"tinygo.org/x/drivers"
+)
 
 // DeviceSPI is the SPI interface to a BMI160 accelerometer/gyroscope. There is
 // also an I2C interface, but it is not yet supported.
@@ -11,13 +14,13 @@ type DeviceSPI struct {
 	CSB machine.Pin
 
 	// SPI bus (requires chip select to be usable).
-	Bus machine.SPI
+	Bus drivers.SPI
 }
 
 // NewSPI returns a new device driver. The pin and SPI interface are not
 // touched, provide a fully configured SPI object and call Configure to start
 // using this device.
-func NewSPI(csb machine.Pin, spi machine.SPI) *DeviceSPI {
+func NewSPI(csb machine.Pin, spi drivers.SPI) *DeviceSPI {
 	return &DeviceSPI{
 		CSB: csb, // chip select
 		Bus: spi,

ds1307/ds1307.go

@@ -42,8 +42,8 @@ func (d *Device) SetTime(t time.Time) error {
 	return err
 }
 
-// Time returns the time and date
-func (d *Device) Time() (time.Time, error) {
+// ReadTime returns the date and time
+func (d *Device) ReadTime() (time.Time, error) {
 	data := make([]byte, 8)
 	err := d.bus.ReadRegister(d.Address, uint8(TimeDate), data)
 	if err != nil {

examples/ds1307/time/main.go

@@ -13,7 +13,7 @@ func main() {
 	rtc.SetTime(time.Date(2019, 5, 15, 20, 34, 12, 0, time.UTC))
 
 	for {
-		t, err := rtc.Time()
+		t, err := rtc.ReadTime()
 		if err != nil {
 			println("Error reading date:", err)
 			break

examples/wifinina/mqttclient/main.go

@@ -41,15 +41,7 @@ var (
 	spi  = machine.NINA_SPI
 
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	adaptor = &wifinina.Device{
-		SPI:   spi,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
-
-	console = machine.UART0
+	adaptor *wifinina.Device
 	topic   = "tinygo"
 )
 
@@ -68,6 +60,11 @@ func main() {
 	})
 
 	// Init esp8266/esp32
+	adaptor = wifinina.New(spi,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
 	adaptor.Configure()
 
 	connectToAP()

examples/wifinina/mqttsub/main.go

@@ -40,15 +40,7 @@ var (
 	spi  = machine.NINA_SPI
 
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	adaptor = &wifinina.Device{
-		SPI:   spi,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
-
-	console = machine.UART0
+	adaptor *wifinina.Device
 
 	cl      mqtt.Client
 	topicTx = "tinygo/tx"
@@ -75,6 +67,11 @@ func main() {
 	})
 
 	// Init esp8266/esp32
+	adaptor = wifinina.New(spi,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
 	adaptor.Configure()
 
 	connectToAP()

examples/wifinina/ntpclient/main.go

@@ -24,20 +24,9 @@ const ntpHost = "129.6.15.29"
 const NTP_PACKET_SIZE = 48
 
 var (
-
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	// these are the default pins for the Arduino Nano33 IoT.
-	adaptor = wifinina.Device{
-		SPI:   machine.NINA_SPI,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
-
-	b = make([]byte, NTP_PACKET_SIZE)
-
-	console = machine.UART0
+	adaptor *wifinina.Device
+	b       = make([]byte, NTP_PACKET_SIZE)
 )
 
 func main() {
@@ -50,6 +39,14 @@ func main() {
 		SDI:       machine.NINA_SDI,
 		SCK:       machine.NINA_SCK,
 	})
+
+	// these are the default pins for the Arduino Nano33 IoT.
+	adaptor = wifinina.New(machine.NINA_SPI,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
+
 	adaptor.Configure()
 
 	// connect to access point

examples/wifinina/tcpclient/main.go

@@ -35,15 +35,7 @@ var (
 	spi  = machine.NINA_SPI
 
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	adaptor = &wifinina.Device{
-		SPI:   spi,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
-
-	console = machine.UART0
+	adaptor *wifinina.Device
 )
 
 var buf = &bytes.Buffer{}
@@ -60,6 +52,11 @@ func main() {
 		SCK:       machine.NINA_SCK,
 	})
 
+	adaptor = wifinina.New(spi,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
 	adaptor.Configure()
 
 	connectToAP()

examples/wifinina/udpstation/main.go

@@ -22,19 +22,9 @@ const pass = ""
 // IP address of the server aka "hub". Replace with your own info.
 const hubIP = ""
 
-// these are the default pins for the Arduino Nano33 IoT.
-// change these to connect to a different UART or pins for the ESP8266/ESP32
 var (
-
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	// these are the default pins for the Arduino Nano33 IoT.
-	adaptor = &wifinina.Device{
-		SPI:   machine.NINA_SPI,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
+	adaptor *wifinina.Device
 )
 
 func main() {
@@ -47,6 +37,14 @@ func main() {
 		SDI:       machine.NINA_SDI,
 		SCK:       machine.NINA_SCK,
 	})
+
+	// these are the default pins for the Arduino Nano33 IoT.
+	// change these to connect to a different UART or pins for the ESP8266/ESP32
+	adaptor = wifinina.New(machine.NINA_SPI,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
 	adaptor.Configure()
 
 	// connect to access point

examples/wifinina/webclient/main.go

@@ -33,15 +33,7 @@ var (
 	spi  = machine.NINA_SPI
 
 	// this is the ESP chip that has the WIFININA firmware flashed on it
-	adaptor = &wifinina.Device{
-		SPI:   spi,
-		CS:    machine.NINA_CS,
-		ACK:   machine.NINA_ACK,
-		GPIO0: machine.NINA_GPIO0,
-		RESET: machine.NINA_RESETN,
-	}
-
-	console = machine.UART0
+	adaptor *wifinina.Device
 )
 
 var buf [256]byte
@@ -61,6 +53,11 @@ func main() {
 		SCK:       machine.NINA_SCK,
 	})
 
+	adaptor = wifinina.New(spi,
+		machine.NINA_CS,
+		machine.NINA_ACK,
+		machine.NINA_GPIO0,
+		machine.NINA_RESETN)
 	adaptor.Configure()
 
 	connectToAP()

examples/ws2812/arduino.go

@@ -0,0 +1,9 @@
+// +build arduino
+
+package main
+
+import "machine"
+
+// Replace neo in the code below to match the pin
+// that you are using if different.
+var neo = machine.D2

examples/ws2812/others.go

@@ -1,4 +1,4 @@
-// +build !digispark
+// +build !digispark,!arduino
 
 package main
 

flash/flash.go

@@ -133,6 +133,8 @@ func (dev *Device) Configure(config *DeviceConfig) (err error) {
 	time.Sleep(30 * time.Microsecond)
 
 	// Speed up to max device frequency
+	// I propose a check here for max frequency, but not put that functionality directly into the driver.
+	// Either that or we have to change the signature of the SPI interface in the machine package itself.
 	if dev.attrs.MaxClockSpeedMHz > 0 {
 		err := dev.trans.setClockSpeed(uint32(dev.attrs.MaxClockSpeedMHz) * 1e6)
 		if err != nil {

flash/transport_spi.go

@@ -1,6 +1,8 @@
 package flash
 
-import "machine"
+import (
+	"machine"
+)
 
 type transport interface {
 	configure(config *DeviceConfig)

hub75/hub75.go

@@ -9,6 +9,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Config struct {
@@ -21,7 +23,7 @@ type Config struct {
 }
 
 type Device struct {
-	bus               machine.SPI
+	bus               drivers.SPI
 	a                 machine.Pin
 	b                 machine.Pin
 	c                 machine.Pin
@@ -52,7 +54,7 @@ type Device struct {
 }
 
 // New returns a new HUB75 driver. Pass in a fully configured SPI bus.
-func New(b machine.SPI, latPin, oePin, aPin, bPin, cPin, dPin machine.Pin) Device {
+func New(b drivers.SPI, latPin, oePin, aPin, bPin, cPin, dPin machine.Pin) Device {
 	aPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	bPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	cPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

mcp3008/mcp3008.go

@@ -7,11 +7,13 @@ package mcp3008 // import "tinygo.org/x/drivers/mcp3008"
 import (
 	"errors"
 	"machine"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps MCP3008 SPI ADC.
 type Device struct {
-	bus machine.SPI
+	bus drivers.SPI
 	cs  machine.Pin
 	tx  []byte
 	rx  []byte
@@ -32,7 +34,7 @@ type ADCPin struct {
 }
 
 // New returns a new MCP3008 driver. Pass in a fully configured SPI bus.
-func New(b machine.SPI, csPin machine.Pin) *Device {
+func New(b drivers.SPI, csPin machine.Pin) *Device {
 	d := &Device{bus: b,
 		cs: csPin,
 		tx: make([]byte, 3),

pcd8544/pcd8544.go

@@ -9,11 +9,13 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an SPI connection.
 type Device struct {
-	bus        machine.SPI
+	bus        drivers.SPI
 	dcPin      machine.Pin
 	rstPin     machine.Pin
 	scePin     machine.Pin
@@ -29,7 +31,7 @@ type Config struct {
 }
 
 // New creates a new PCD8544 connection. The SPI bus must already be configured.
-func New(bus machine.SPI, dcPin, rstPin, scePin machine.Pin) *Device {
+func New(bus drivers.SPI, dcPin, rstPin, scePin machine.Pin) *Device {
 	return &Device{
 		bus:    bus,
 		dcPin:  dcPin,

spi.go

@@ -0,0 +1,13 @@
+package drivers
+
+// SPI represents a SPI bus. It is implemented by the machine.SPI type.
+type SPI interface {
+	// Tx transmits the given buffer w and receives at the same time the buffer r.
+	// The two buffers must be the same length. The only exception is when w or r are nil,
+	// in which case Tx only transmits (without receiving) or only receives (while sending 0 bytes).
+	Tx(w, r []byte) error
+
+	// Transfer writes a single byte out on the SPI bus and receives a byte at the same time.
+	// If you want to transfer multiple bytes, it is more efficient to use Tx instead.
+	Transfer(b byte) (byte, error)
+}

ssd1306/ssd1306.go

@@ -37,7 +37,7 @@ type I2CBus struct {
 }
 
 type SPIBus struct {
-	wire     machine.SPI
+	wire     drivers.SPI
 	dcPin    machine.Pin
 	resetPin machine.Pin
 	csPin    machine.Pin
@@ -62,7 +62,7 @@ func NewI2C(bus drivers.I2C) Device {
 }
 
 // NewSPI creates a new SSD1306 connection. The SPI wire must already be configured.
-func NewSPI(bus machine.SPI, dcPin, resetPin, csPin machine.Pin) Device {
+func NewSPI(bus drivers.SPI, dcPin, resetPin, csPin machine.Pin) Device {
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

ssd1331/ssd1331.go

@@ -10,6 +10,8 @@ import (
 
 	"errors"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Model uint8
@@ -17,7 +19,7 @@ type Rotation uint8
 
 // Device wraps an SPI connection.
 type Device struct {
-	bus         machine.SPI
+	bus         drivers.SPI
 	dcPin       machine.Pin
 	resetPin    machine.Pin
 	csPin       machine.Pin
@@ -35,7 +37,7 @@ type Config struct {
 }
 
 // New creates a new SSD1331 connection. The SPI wire must already be configured.
-func New(bus machine.SPI, resetPin, dcPin, csPin machine.Pin) Device {
+func New(bus drivers.SPI, resetPin, dcPin, csPin machine.Pin) Device {
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

ssd1351/ssd1351.go

@@ -9,6 +9,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 var (
@@ -18,7 +20,7 @@ var (
 
 // Device wraps an SPI connection.
 type Device struct {
-	bus          machine.SPI
+	bus          drivers.SPI
 	dcPin        machine.Pin
 	resetPin     machine.Pin
 	csPin        machine.Pin
@@ -40,7 +42,7 @@ type Config struct {
 }
 
 // New creates a new SSD1351 connection. The SPI wire must already be configured.
-func New(bus machine.SPI, resetPin, dcPin, csPin, enPin, rwPin machine.Pin) Device {
+func New(bus drivers.SPI, resetPin, dcPin, csPin, enPin, rwPin machine.Pin) Device {
 	return Device{
 		bus:      bus,
 		dcPin:    dcPin,

st7735/st7735.go

@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"errors"
+
+	"tinygo.org/x/drivers"
 )
 
 type Model uint8
@@ -17,7 +19,7 @@ type Rotation uint8
 
 // Device wraps an SPI connection.
 type Device struct {
-	bus          machine.SPI
+	bus          drivers.SPI
 	dcPin        machine.Pin
 	resetPin     machine.Pin
 	csPin        machine.Pin
@@ -44,7 +46,7 @@ type Config struct {
 }
 
 // New creates a new ST7735 connection. The SPI wire must already be configured.
-func New(bus machine.SPI, resetPin, dcPin, csPin, blPin machine.Pin) Device {
+func New(bus drivers.SPI, resetPin, dcPin, csPin, blPin machine.Pin) Device {
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

st7789/st7789.go

@@ -12,6 +12,8 @@ import (
 	"time"
 
 	"errors"
+
+	"tinygo.org/x/drivers"
 )
 
 type Rotation uint8
@@ -20,7 +22,7 @@ type FrameRate uint8
 
 // Device wraps an SPI connection.
 type Device struct {
-	bus             machine.SPI
+	bus             drivers.SPI
 	dcPin           machine.Pin
 	resetPin        machine.Pin
 	csPin           machine.Pin
@@ -50,7 +52,7 @@ type Config struct {
 }
 
 // New creates a new ST7789 connection. The SPI wire must already be configured.
-func New(bus machine.SPI, resetPin, dcPin, csPin, blPin machine.Pin) Device {
+func New(bus drivers.SPI, resetPin, dcPin, csPin, blPin machine.Pin) Device {
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	resetPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
@@ -276,7 +278,6 @@ func (d *Device) FillRectangle(x, y, width, height int16, c color.RGBA) error {
 	return nil
 }
 
-
 // FillRectangle fills a rectangle at a given coordinates with a buffer
 func (d *Device) FillRectangleWithBuffer(x, y, width, height int16, buffer []color.RGBA) error {
 	i, j := d.Size()

waveshare-epd/epd2in13/epd2in13.go

@@ -9,6 +9,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Config struct {
@@ -19,7 +21,7 @@ type Config struct {
 }
 
 type Device struct {
-	bus          machine.SPI
+	bus          drivers.SPI
 	cs           machine.Pin
 	dc           machine.Pin
 	rst          machine.Pin
@@ -51,7 +53,7 @@ var lutPartialUpdate = [30]uint8{
 }
 
 // New returns a new epd2in13x driver. Pass in a fully configured SPI bus.
-func New(bus machine.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
+func New(bus drivers.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	rstPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

waveshare-epd/epd2in13x/epd2in13x.go

@@ -9,6 +9,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Config struct {
@@ -18,7 +20,7 @@ type Config struct {
 }
 
 type Device struct {
-	bus          machine.SPI
+	bus          drivers.SPI
 	cs           machine.Pin
 	dc           machine.Pin
 	rst          machine.Pin
@@ -32,7 +34,7 @@ type Device struct {
 type Color uint8
 
 // New returns a new epd2in13x driver. Pass in a fully configured SPI bus.
-func New(bus machine.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
+func New(bus drivers.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	rstPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

waveshare-epd/epd4in2/epd4in2.go

@@ -12,6 +12,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Config struct {
@@ -22,7 +24,7 @@ type Config struct {
 }
 
 type Device struct {
-	bus          machine.SPI
+	bus          drivers.SPI
 	cs           machine.Pin
 	dc           machine.Pin
 	rst          machine.Pin
@@ -38,7 +40,7 @@ type Device struct {
 type Rotation uint8
 
 // New returns a new epd4in2 driver. Pass in a fully configured SPI bus.
-func New(bus machine.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
+func New(bus drivers.SPI, csPin, dcPin, rstPin, busyPin machine.Pin) Device {
 	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	rstPin.Configure(machine.PinConfig{Mode: machine.PinOutput})

wifinina/wifinina.go

@@ -13,6 +13,7 @@ import (
 
 	"machine"
 
+	"tinygo.org/x/drivers"
 	"tinygo.org/x/drivers/net"
 )
 
@@ -258,7 +259,7 @@ type command struct {
 }
 
 type Device struct {
-	SPI   machine.SPI
+	SPI   drivers.SPI
 	CS    machine.Pin
 	ACK   machine.Pin
 	GPIO0 machine.Pin
@@ -268,6 +269,17 @@ type Device struct {
 	ssids [10]string
 }
 
+// New returns a new Wifinina driver.
+func New(bus drivers.SPI, csPin, ackPin, gpio0Pin, resetPin machine.Pin) *Device {
+	return &Device{
+		SPI:   bus,
+		CS:    csPin,
+		ACK:   ackPin,
+		GPIO0: gpio0Pin,
+		RESET: resetPin,
+	}
+}
+
 func (d *Device) Configure() {
 
 	net.UseDriver(d.NewDriver())

ws2812/ws2812.go

@@ -2,10 +2,15 @@
 package ws2812 // import "tinygo.org/x/drivers/ws2812"
 
 import (
+	"errors"
 	"image/color"
 	"machine"
+
+	"tinygo.org/x/drivers"
 )
 
+var errUnknownClockSpeed = errors.New("ws2812: unknown CPU clock speed")
+
 // Device wraps a pin object for an easy driver interface.
 type Device struct {
 	Pin machine.Pin
@@ -35,3 +40,77 @@ func (d Device) WriteColors(buf []color.RGBA) error {
 	}
 	return nil
 }
+
+// DeviceSPI wraps a SPI object for driving a string of WS2812 LEDs.
+type DeviceSPI struct {
+	Bus drivers.SPI
+
+	// Use a buffer embedded in the device struct so that at most one allocation
+	// happens at NewSPI and no allocation during transmission.
+	buf []byte
+}
+
+// NewSPI returns a WS2812 driver using a SPI bus. This SPI bus must already be
+// configured at exactly 4MHz otherwise WS2812 won't work properly with it.
+//
+// The advantage of using a SPI bus over bitbanging is that it doesn't require
+// custom assembly for each new platform and that it may avoid needing to
+// disable interrupts while sending color data if the SPI peripheral uses DMA.
+// The disadvantage is of course that it is limited in which pins can be used
+// for WS2812 output.
+func NewSPI(bus drivers.SPI) *DeviceSPI {
+	return &DeviceSPI{
+		Bus: bus,
+	}
+}
+
+// WriteColors wries the given color slice out using the WS2812 protocol.
+// Colors are sent out in the usual GRB format.
+func (d *DeviceSPI) WriteColors(buf []color.RGBA) error {
+	// Each color needs 15 bytes: 5 SPI bits per WS2812 bit with 3*8 WS2812 bits
+	// per color means 120 SPI bits. In addition to that, an extra 0 byte seems
+	// to be necessary on nRF5x chips to avoid having the SDO line pulled high
+	// at the end of the transfer.
+	if len(d.buf) < len(buf)*15+1 {
+		d.buf = make([]byte, len(buf)*15+1)
+	}
+
+	for i, color := range buf {
+		bitBuf := makeSPIBits(color.G)
+		copy(d.buf[i*15+0:], bitBuf[:])
+		bitBuf = makeSPIBits(color.R)
+		copy(d.buf[i*15+5:], bitBuf[:])
+		bitBuf = makeSPIBits(color.B)
+		copy(d.buf[i*15+10:], bitBuf[:])
+	}
+	return d.Bus.Tx(d.buf, nil)
+}
+
+func makeSPIBits(b byte) [5]byte {
+	// Create a 40 bit bitstring from this one byte.
+	var bitstring uint64
+	for i := 0; i < 8; i++ {
+		bitstring <<= 5
+		if b&0x80 != 0 {
+			// 0b11100 means the output is high for 750ns (three high bits at
+			// 4MHz) and low for 500ns (two low bits). This outputs a 1 bit in
+			// the custom WS2812 protocol.
+			bitstring |= 0b11100 // T1H (0b111) + TLD (0b00)
+		} else {
+			// 0b10000 means the output is high for 250ns (one high bit at 4MHz)
+			// and low for 1000ns (four low bits at 4MHz). This outputs a 0 bit
+			// in the custom WS2812 protocol.
+			bitstring |= 0b10000 // T0H (0b100) + TLD (0b00)
+		}
+		b <<= 1
+	}
+
+	// Create a 5 byte array from this bitstring.
+	bitstring <<= 7
+	var buf [5]byte
+	for i := 0; i < 5; i++ {
+		buf[i] = byte(bitstring >> 40)
+		bitstring <<= 8
+	}
+	return buf
+}

ws2812/ws2812_avr.go

@@ -0,0 +1,58 @@
+// +build avr
+
+package ws2812
+
+// This file implements the WS2812 protocol for AVR microcontrollers.
+
+import (
+	"device/avr"
+	"machine"
+)
+
+// Send a single byte using the WS2812 protocol.
+func (d Device) WriteByte(c byte) error {
+	// On AVR, the port is always the same for setting and clearing a register
+	// so use only one. This avoids the following error:
+	//     error: inline assembly requires more registers than available
+	// Probably this is about pointer registers, which are very limited on AVR.
+	port, maskSet := d.Pin.PortMaskSet()
+	_, maskClear := d.Pin.PortMaskClear()
+
+	switch machine.CPUFrequency() {
+	case 16e6: // 16MHz
+		// See:
+		// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
+		// T0H: 4  cycles or 250ns
+		// T0L: 14 cycles or 875ns -> together 18 cycles or 1125ns
+		// T1H: 9  cycles or 562ns
+		// T1L: 8  cycles or 500ns -> together 17 cycles or 1062ns
+		avr.AsmFull(`
+	send_bit:
+		st    {portSet}, {maskSet}     ; [2]   set output high
+		lsl   {value}                  ; [1]   shift off the next bit, store it in C
+		brcs  skip_store               ; [1/2] branch if this bit is high (long pulse)
+		st    {portClear}, {maskClear} ; [2]   set output low (short pulse)
+	skip_store:
+		nop                            ; [4]   wait before changing the output again
+		nop
+		nop
+		nop
+		st    {portClear}, {maskClear} ; [2]   set output low (end of pulse)
+		nop                            ; [3]
+		nop
+		nop
+		subi  {i}, 1                   ; [1]   subtract one (for the loop)
+		brne  send_bit                 ; [1/2] send the next bit, if not at the end of the loop
+	`, map[string]interface{}{
+			"value":     c,
+			"i":         byte(8),
+			"maskSet":   maskSet,
+			"portSet":   port,
+			"maskClear": maskClear,
+			"portClear": port,
+		})
+		return nil
+	default:
+		return errUnknownClockSpeed
+	}
+}

ws2812/ws2812_avr_16m.go

@@ -1,49 +0,0 @@
-// +build atmega328p
-
-package ws2812
-
-// This file implements the WS2812 protocol for 16MHz AVR microcontrollers.
-
-import (
-	"device/avr"
-)
-
-// Send a single byte using the WS2812 protocol.
-func (d Device) WriteByte(c byte) error {
-	// For the AVR at 16MHz
-	portSet, maskSet := d.Pin.PortMaskSet()
-	portClear, maskClear := d.Pin.PortMaskClear()
-
-	// See:
-	// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
-	// T0H: 4  cycles or 250ns
-	// T0L: 14 cycles or 875ns -> together 18 cycles or 1125ns
-	// T1H: 9  cycles or 562ns
-	// T1L: 8  cycles or 500ns -> together 17 cycles or 1062ns
-	avr.AsmFull(`
-	send_bit:
-		st    {portSet}, {maskSet}     ; [2]   set output high
-		lsl   {value}                  ; [1]   shift off the next bit, store it in C
-		brcs  skip_store               ; [1/2] branch if this bit is high (long pulse)
-		st    {portClear}, {maskClear} ; [2]   set output low (short pulse)
-	skip_store:
-		nop                            ; [4]   wait before changing the output again
-		nop
-		nop
-		nop
-		st    {portClear}, {maskClear} ; [2]   set output low (end of pulse)
-		nop                            ; [3]
-		nop
-		nop
-		subi  {i}, 1                   ; [1]   subtract one (for the loop)
-		brne  send_bit                 ; [1/2] send the next bit, if not at the end of the loop
-	`, map[string]interface{}{
-		"value":     c,
-		"i":         8,
-		"maskSet":   maskSet,
-		"portSet":   portSet,
-		"maskClear": maskClear,
-		"portClear": portClear,
-	})
-	return nil
-}

ws2812/ws2812_avr_digispark.go

@@ -1,50 +0,0 @@
-// +build digispark
-
-package ws2812
-
-// This file implements the WS2812 protocol for 16.5MHz Digispark AVR microcontrollers.
-// This is a slightly different implementation than the one for the atmega to work around a compiler bug.
-
-import (
-	"device/avr"
-)
-
-// Send a single byte using the WS2812 protocol.
-func (d Device) WriteByte(c byte) error {
-	// For the AVR at 16MHz
-	portSet, maskSet := d.Pin.PortMaskSet()
-	portClear, maskClear := d.Pin.PortMaskClear()
-
-	// See:
-	// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
-	// T0H: 4  cycles or 250ns
-	// T0L: 14 cycles or 875ns -> together 18 cycles or 1125ns
-	// T1H: 9  cycles or 562ns
-	// T1L: 8  cycles or 500ns -> together 17 cycles or 1062ns
-	avr.AsmFull(`
-	send_bit:
-		st    {portSet}, {maskSet}     ; [2]   set output high
-		lsl   {value}                  ; [1]   shift off the next bit, store it in C
-		brcs  skip_store               ; [1/2] branch if this bit is high (long pulse)
-		st    {portClear}, {maskClear} ; [2]   set output low (short pulse)
-	skip_store:
-		nop                            ; [4]   wait before changing the output again
-		nop
-		nop
-		nop
-		st    {portClear}, {maskClear} ; [2]   set output low (end of pulse)
-		nop                            ; [3]
-		nop
-		nop
-		subi  {i}, 1                   ; [1]   subtract one (for the loop)
-		brne  send_bit                 ; [1/2] send the next bit, if not at the end of the loop
-	`, map[string]interface{}{
-		"value":     c,
-		"i":         byte(8),
-		"maskSet":   maskSet,
-		"portSet":   portSet,
-		"maskClear": maskClear,
-		"portClear": portClear,
-	})
-	return nil
-}

ws2812/ws2812_xtensa.go

@@ -4,13 +4,10 @@ package ws2812
 
 import (
 	"device"
-	"errors"
 	"machine"
 	"unsafe"
 )
 
-var errUnknownClockSpeed = errors.New("ws2812: unknown CPU clock speed")
-
 func (d Device) WriteByte(c byte) error {
 	portSet, maskSet := d.Pin.PortMaskSet()
 	portClear, maskClear := d.Pin.PortMaskClear()