Prepare for Drivers release 0.14.0

Signed-off-by: deadprogram <ron@hybridgroup.com>

CHANGELOG.md

@@ -1,3 +1,35 @@
+0.14.0
+---
+- **new devices**
+    - lis2mdl: add LIS2MDL magnetometer (#187)
+    - waveshare: add Waveshare 4.2in B/W e-paper driver (#183)
+- **enhancements**
+    - adt7410: add connection test and for that matter connection method
+    - gps
+        - add speed and heading to fix, as parsed from RMC NMEA sentence
+        - improvements and bugfixes (#186)
+    - ili9341
+        - add support for setting framerate, vsync pause, and reading scanline data.
+        - renamed NewSpi() to NewSPI() in accordance with Go naming conventions
+    - ws2812
+        - add support for ESP8266
+        - add support for ESP32
+- **bugfixes**
+    - ili9341
+        - rix setWindow bug, add CS pin for Clue compatibility. (#180)
+        - bugfix for RAMWR bug
+    - lis2mdl: turn on read mode on every read, to ensure that magnetometer data is updated
+- **core**
+    - i2c
+        - switch all i2c drivers definitions to use i2c bus interface type instead of machine package concrete type
+        - correct interface definition for I2C Tx function
+- **testing**
+    - fix smoke-test unless avr-gcc installed
+    - add very basic mock structs for testing i2c devices, based on work done by @rogpeppe
+    - improve API surface and implement one more test function in lis2mdl driver
+- **docs**
+    - replace README badge for godocs with pkgdocs
+
 0.13.0
 ---
 - **new devices**

Makefile

@@ -119,6 +119,8 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/waveshare-epd/epd2in13x/main.go
 	@md5sum ./build/test.hex
+	tinygo build -size short -o ./build/test.hex -target=microbit ./examples/waveshare-epd/epd4in2/main.go
+	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=arduino-nano33 ./examples/wifinina/ntpclient/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=arduino-nano33 ./examples/wifinina/udpstation/main.go
@@ -129,8 +131,10 @@ smoke-test:
 	@md5sum ./build/test.hex
 	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=digispark ./examples/ws2812
 	@md5sum ./build/test.hex
+endif
 	tinygo build -size short -o ./build/test.hex -target=trinket-m0 ./examples/bme280/main.go
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=circuitplay-express ./examples/microphone/main.go
@@ -151,5 +155,7 @@ smoke-test:
 	@md5sum ./build/test.hex
 	tinygo build -size short -o ./build/test.hex -target=hifive1b ./examples/ssd1351/main.go
 	@md5sum ./build/test.hex
+	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

README.md

@@ -1,6 +1,6 @@
 # TinyGo Drivers
 
-[![GoDoc](https://godoc.org/tinygo.org/x/drivers?status.svg)](https://godoc.org/tinygo.org/x/drivers) [![CircleCI](https://circleci.com/gh/tinygo-org/drivers/tree/dev.svg?style=svg)](https://circleci.com/gh/tinygo-org/drivers/tree/dev)
+[![PkgGoDev](https://pkg.go.dev/badge/tinygo.org/x/drivers)](https://pkg.go.dev/tinygo.org/x/drivers) [![CircleCI](https://circleci.com/gh/tinygo-org/drivers/tree/dev.svg?style=svg)](https://circleci.com/gh/tinygo-org/drivers/tree/dev)
 
 
 This package provides a collection of hardware drivers for devices that can be used together with [TinyGo](https://tinygo.org).
@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 51 devices are supported.
+The following 53 devices are supported.
 
 | Device Name | Interface Type |
 |----------|-------------|
@@ -80,6 +80,7 @@ The following 51 devices are supported.
 | [ILI9341 TFT color display](https://cdn-shop.adafruit.com/datasheets/ILI9341.pdf) | SPI |
 | [L293x motor driver](https://www.ti.com/lit/ds/symlink/l293d.pdf) | GPIO/PWM |
 | [L9110x motor driver](https://www.elecrow.com/download/datasheet-l9110.pdf) | GPIO/PWM |
+| [LIS2MDL magnetometer](https://www.st.com/resource/en/datasheet/lis2mdl.pdf) | I2C |
 | [LIS3DH accelerometer](https://www.st.com/resource/en/datasheet/lis3dh.pdf) | I2C |
 | [LSM6DS3 accelerometer](https://www.st.com/resource/en/datasheet/lsm6ds3.pdf) | I2C |
 | [MAG3110 magnetometer](https://www.nxp.com/docs/en/data-sheet/MAG3110.pdf) | I2C |
@@ -106,6 +107,7 @@ The following 51 devices are supported.
 | [VL53L1X time-of-flight distance sensor](https://www.st.com/resource/en/datasheet/vl53l1x.pdf) | I2C |
 | [Waveshare 2.13" (B & C) e-paper display](https://www.waveshare.com/w/upload/d/d3/2.13inch-e-paper-b-Specification.pdf) | SPI |
 | [Waveshare 2.13" e-paper display](https://www.waveshare.com/w/upload/e/e6/2.13inch_e-Paper_Datasheet.pdf) | SPI |
+| [Waveshare 4.2" e-paper B/W display](https://www.waveshare.com/w/upload/6/6a/4.2inch-e-paper-specification.pdf) | SPI |
 | [WS2812 RGB LED](https://cdn-shop.adafruit.com/datasheets/WS2812.pdf) | GPIO |
 
 ## Contributing

adt7410/adt7410.go

@@ -1,8 +1,13 @@
+// Package adt7410 provides a driver for the adt7410 I2C Temperature Sensor.
+//
+// Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADT7410.pdf
+//
 package adt7410 // import "tinygo.org/x/drivers/adt7410"
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Error uint8
@@ -21,40 +26,37 @@ func (e Error) Error() string {
 }
 
 type Device struct {
-	bus  *machine.I2C
-	buf  []byte
-	addr uint8
+	bus     drivers.I2C
+	buf     []byte
+	Address uint8
 }
 
-// New returns ADT7410 device for the provided I2C bus and address. The ADT7410
-// has a default address of 0x48 (1001000).  The last 2 bits of the address
+// New returns ADT7410 device for the provided I2C bus using default address.
+// of 0x48 (1001000).  To use multiple ADT7410 devices, the last 2 bits of the address
 // can be set using by connecting to the A1 and A0 pins to VDD or GND (for a
 // total of up to 4 devices on a I2C bus).  Also note that 10k pullups are
 // recommended for the SDA and SCL lines.
-func New(i2c *machine.I2C, addressBits uint8) *Device {
+func New(i2c drivers.I2C) *Device {
 	return &Device{
-		bus:  i2c,
-		buf:  make([]byte, 2),
-		addr: Address | (addressBits & 0x3),
+		bus:     i2c,
+		buf:     make([]byte, 2),
+		Address: Address,
 	}
 }
 
-func (dev *Device) Configure() (err error) {
-
-	// verify the chip ID
-	// TODO: According to datasheet, the check below should work; however
-	//       this does not seem to be working right, but is not exactly
-	//       necessary, so can revisit later to see if there is a bug
-	//id := dev.ReadByte(RegID) & 0xF8
-	//if id != 0xC8 {
-	//	err = ErrInvalidID
-	//}
-
+// Configure the ADT7410 device.
+func (d *Device) Configure() (err error) {
 	// reset the chip
-	dev.writeByte(RegReset, 0xFF)
+	d.writeByte(RegReset, 0xFF)
 	time.Sleep(10 * time.Millisecond)
 	return
+}
 
+// Connected returns whether sensor has been found.
+func (d *Device) Connected() bool {
+	data := []byte{0}
+	d.bus.ReadRegister(uint8(d.Address), RegID, data)
+	return data[0]&0xF8 == 0xC8
 }
 
 // ReadTemperature returns the temperature in celsius milli degrees (°C/1000)
@@ -62,13 +64,13 @@ func (d *Device) ReadTemperature() (temperature int32, err error) {
 	return (int32(d.readUint16(RegTempValueMSB)) * 1000) / 128, nil
 }
 
-// ReadTempC returns the value in the temperature value register, in Celcius
+// ReadTempC returns the value in the temperature value register, in Celsius.
 func (d *Device) ReadTempC() float32 {
 	t := d.readUint16(RegTempValueMSB)
 	return float32(int(t)) / 128.0
 }
 
-// ReadTempF returns the value in the temperature value register, in Fahrenheit
+// ReadTempF returns the value in the temperature value register, in Fahrenheit.
 func (d *Device) ReadTempF() float32 {
 	return d.ReadTempC()*1.8 + 32.0
 }
@@ -76,15 +78,15 @@ func (d *Device) ReadTempF() float32 {
 func (d *Device) writeByte(reg uint8, data byte) {
 	d.buf[0] = reg
 	d.buf[1] = data
-	d.bus.Tx(uint16(d.addr), d.buf, nil)
+	d.bus.Tx(uint16(d.Address), d.buf, nil)
 }
 
 func (d *Device) readByte(reg uint8) byte {
-	d.bus.ReadRegister(d.addr, reg, d.buf)
+	d.bus.ReadRegister(d.Address, reg, d.buf)
 	return d.buf[0]
 }
 
 func (d *Device) readUint16(reg uint8) uint16 {
-	d.bus.ReadRegister(d.addr, reg, d.buf)
+	d.bus.ReadRegister(d.Address, reg, d.buf)
 	return uint16(d.buf[0])<<8 | uint16(d.buf[1])
 }

adt7410/adt7410_test.go

@@ -0,0 +1,49 @@
+package adt7410
+
+import (
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"tinygo.org/x/drivers/tester"
+)
+
+func TestDefaultI2CAddress(t *testing.T) {
+	c := qt.New(t)
+	bus := tester.NewI2CBus(c)
+	dev := New(bus)
+	c.Assert(dev.Address, qt.Equals, uint8(Address))
+}
+
+func TestWhoAmI(t *testing.T) {
+	c := qt.New(t)
+	bus := tester.NewI2CBus(c)
+	fake := tester.NewI2CDevice(c, Address)
+	fake.SetupRegisters(defaultRegisters())
+	bus.AddDevice(fake)
+
+	dev := New(bus)
+	c.Assert(dev.Connected(), qt.Equals, true)
+
+	fake.SetupRegister(RegID, 0x99)
+	c.Assert(dev.Connected(), qt.Equals, false)
+}
+
+// defaultRegisters returns the default values for all of the device's registers.
+// see table 22 on page 27 of the datasheet.
+func defaultRegisters() []uint8 {
+	return []uint8{
+		RegTempValueMSB: 0,
+		RegTempValueLSB: 0,
+		RegStatus:       0,
+		RegConfig:       0,
+		RegTHIGHMsbReg:  0x20,
+		RegTHIGHLsbReg:  0,
+		RegTLOWMsbReg:   0x05,
+		RegTLOWLsbReg:   0,
+		RegTCRITMsbReg:  0x49,
+		RegTCRITLsbReg:  0x80,
+		RegTHYSTReg:     0x05,
+		RegID:           0xC8,
+		RegReset:        0,
+	}
+}

adt7410/registers.go

@@ -1,8 +1,33 @@
 package adt7410
 
+// 0x00 Temperature value most significant byte 0x00
+// 0x01 Temperature value least significant byte 0x00
+// 0x02 Status 0x00
+// 0x03 Configuration 0x00
+// 0x04 THIGH setpoint most significant byte 0x20 (64°C)
+// 0x05 THIGH setpoint least significant byte 0x00 (64°C)
+// 0x06 TLOW setpoint most significant byte 0x05 (10°C)
+// 0x07 TLOW setpoint least significant byte 0x00 (10°C)
+// 0x08 TCRIT setpoint most significant byte 0x49 (147°C)
+// 0x09 TCRIT setpoint least significant byte 0x80 (147°C)
+// 0x0A THYST setpoint 0x05 (5°C)
+// 0x0B ID 0xCX
+// 0x0C Reserved 0xXX
+// 0x0D Reserved 0xXX
+// 0x2E Reserved 0xXX
+// 0x2F Software reset 0xXX
+
 const (
-	// Default I2C address
+	// Address is default I2C address.
 	Address = 0x48
+	// Address1 is for first device, aka the default.
+	Address1 = Address
+	// Address2 is for second device.
+	Address2 = 0x49
+	// Address3 is for third device.
+	Address3 = 0x4A
+	// Address4 is for fourth device.
+	Address4 = 0x4B
 
 	// Temperature Value MSB Register
 	RegTempValueMSB = 0x0
@@ -16,7 +41,28 @@ const (
 	// Config Register
 	RegConfig = 0x3
 
-	// ID Register
+	// THIGH setpoint most significant byte 0x20 (64°C)
+	RegTHIGHMsbReg = 0x4
+
+	// THIGH setpoint least significant byte 0x00 (64°C)
+	RegTHIGHLsbReg = 0x5
+
+	// TLOW setpoint most significant byte 0x05 (10°C)
+	RegTLOWMsbReg = 0x6
+
+	// TLOW setpoint least significant byte 0x00 (10°C)
+	RegTLOWLsbReg = 0x7
+
+	// TCRIT setpoint most significant byte 0x49 (147°C)
+	RegTCRITMsbReg = 0x8
+
+	// TCRIT setpoint least significant byte 0x80 (147°C)
+	RegTCRITLsbReg = 0x9
+
+	// THYST setpoint 0x05 (5°C)
+	RegTHYSTReg = 0xA
+
+	// ID Register (0xCx)
 	RegID = 0x0B
 
 	// Software Reset Register

adxl345/adxl345.go

@@ -6,9 +6,7 @@
 //
 package adxl345 // import "tinygo.org/x/drivers/adxl345"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 type Range uint8
 type Rate uint8
@@ -40,7 +38,7 @@ type bwRate struct {
 
 // Device wraps an I2C connection to a ADXL345 device.
 type Device struct {
-	bus        machine.I2C
+	bus        drivers.I2C
 	Address    uint16
 	powerCtl   powerCtl
 	dataFormat dataFormat
@@ -52,7 +50,7 @@ type Device struct {
 //
 // This function only creates the Device object, it does not init the device.
 // To do that you must call the Configure() method on the Device before using it.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus: bus,
 		powerCtl: powerCtl{

amg88xx/amg88xx.go

@@ -5,13 +5,14 @@
 package amg88xx // import "tinygo.org/x/drivers/amg88xx"
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a AMG88xx device.
 type Device struct {
-	bus             machine.I2C
+	bus             drivers.I2C
 	Address         uint16
 	data            []uint8
 	interruptMode   InterruptMode
@@ -27,7 +28,7 @@ type Config struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: AddressHigh,

at24cx/at24cx.go

@@ -6,13 +6,14 @@ package at24cx // import "tinygo.org/x/drivers/at24cx"
 
 import (
 	"errors"
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a DS3231 device.
 type Device struct {
-	bus               machine.I2C
+	bus               drivers.I2C
 	Address           uint16
 	pageSize          uint16
 	currentRAMAddress uint16
@@ -30,7 +31,7 @@ type Config struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

bh1750/bh1750.go

@@ -8,7 +8,7 @@ package bh1750 // import "tinygo.org/x/drivers/bh1750"
 import (
 	"time"
 
-	"machine"
+	"tinygo.org/x/drivers"
 )
 
 // SamplingMode is the sampling's resolution of the measurement
@@ -16,7 +16,7 @@ type SamplingMode byte
 
 // Device wraps an I2C connection to a bh1750 device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 	mode    SamplingMode
 }
@@ -25,7 +25,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

blinkm/blinkm.go

@@ -1,15 +1,14 @@
 // Package blinkm implements a driver for the BlinkM I2C RGB LED.
 //
 // Datasheet: http://thingm.com/fileadmin/thingm/downloads/BlinkM_datasheet.pdf
+//
 package blinkm // import "tinygo.org/x/drivers/blinkm"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device wraps an I2C connection to a BlinkM device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 }
 
@@ -17,7 +16,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus, Address}
 }
 

bme280/bme280.go

@@ -7,8 +7,9 @@
 package bme280
 
 import (
-	"machine"
 	"math"
+
+	"tinygo.org/x/drivers"
 )
 
 // calibrationCoefficients reads at startup and stores the calibration coefficients
@@ -35,7 +36,7 @@ type calibrationCoefficients struct {
 
 // Device wraps an I2C connection to a BME280 device.
 type Device struct {
-	bus                     machine.I2C
+	bus                     drivers.I2C
 	Address                 uint16
 	calibrationCoefficients calibrationCoefficients
 }
@@ -44,7 +45,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

bmp180/bmp180.go

@@ -9,7 +9,7 @@ package bmp180 // import "tinygo.org/x/drivers/bmp180"
 import (
 	"time"
 
-	"machine"
+	"tinygo.org/x/drivers"
 )
 
 // OversamplingMode is the oversampling ratio of the pressure measurement.
@@ -32,7 +32,7 @@ type calibrationCoefficients struct {
 
 // Device wraps an I2C connection to a BMP180 device.
 type Device struct {
-	bus                     machine.I2C
+	bus                     drivers.I2C
 	Address                 uint16
 	mode                    OversamplingMode
 	calibrationCoefficients calibrationCoefficients
@@ -43,7 +43,7 @@ type Device struct {
 //
 // This function only creates the Device object, it does not initialize the device.
 // You must call Configure() first in order to use the device itself.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

bmp280/bmp280.go

@@ -1,8 +1,9 @@
 package bmp280
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // OversamplingMode is the oversampling ratio of the temperature or pressure measurement.
@@ -19,7 +20,7 @@ type Filter uint
 
 // Device wraps an I2C connection to a BMP280 device.
 type Device struct {
-	bus         machine.I2C
+	bus         drivers.I2C
 	Address     uint16
 	cali        calibrationCoefficients
 	Temperature Oversampling
@@ -52,7 +53,7 @@ type calibrationCoefficients struct {
 //
 // This function only creates the Device object, it does not initialize the device.
 // You must call Configure() first in order to use the device itself.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

ds1307/ds1307.go

@@ -9,18 +9,18 @@ import (
 	"errors"
 	"time"
 
-	"machine"
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a DS1307 device.
 type Device struct {
-	bus         machine.I2C
+	bus         drivers.I2C
 	Address     uint8
 	AddressSRAM uint8
 }
 
 // New creates a new DS1307 connection. I2C bus must be already configured.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus: bus,
 		Address:     uint8(I2CAddress),
 		AddressSRAM: SRAMBeginAddres,

ds3231/ds3231.go

@@ -5,15 +5,16 @@
 package ds3231 // import "tinygo.org/x/drivers/ds3231"
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type Mode uint8
 
 // Device wraps an I2C connection to a DS3231 device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 }
 
@@ -21,7 +22,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

examples/adt7410/main.go

@@ -10,7 +10,7 @@ import (
 
 var (
 	i2c    = &machine.I2C0
-	sensor = adt7410.New(i2c, 0)
+	sensor = adt7410.New(i2c)
 )
 
 func main() {

examples/gps/i2c/main.go

@@ -1,8 +1,8 @@
 package main
 
 import (
-	"fmt"
 	"machine"
+	"time"
 
 	"tinygo.org/x/drivers/gps"
 )
@@ -11,19 +11,40 @@ func main() {
 	println("GPS I2C Example")
 	machine.I2C0.Configure(machine.I2CConfig{})
 	ublox := gps.NewI2C(&machine.I2C0)
-	parser := gps.Parser(ublox)
+	parser := gps.NewParser()
 	var fix gps.Fix
 	for {
-		fix = parser.NextFix()
+		s, err := ublox.NextSentence()
+		if err != nil {
+			println(err)
+			continue
+		}
+
+		fix, err = parser.Parse(s)
+		if err != nil {
+			println(err)
+			continue
+		}
 		if fix.Valid {
 			print(fix.Time.Format("15:04:05"))
-			print(", lat=", fmt.Sprintf("%f", fix.Latitude))
-			print(", long=", fmt.Sprintf("%f", fix.Longitude))
-			print(", altitude:=", fix.Altitude)
+			print(", lat=")
+			print(fix.Latitude)
+			print(", long=")
+			print(fix.Longitude)
+			print(", altitude=", fix.Altitude)
 			print(", satellites=", fix.Satellites)
+			if fix.Speed != 0 {
+				print(", speed=")
+				print(fix.Speed)
+			}
+			if fix.Heading != 0 {
+				print(", heading=")
+				print(fix.Heading)
+			}
 			println()
 		} else {
 			println("No fix")
 		}
+		time.Sleep(200 * time.Millisecond)
 	}
 }

examples/gps/uart/main.go

@@ -1,8 +1,8 @@
 package main
 
 import (
-	"fmt"
 	"machine"
+	"time"
 
 	"tinygo.org/x/drivers/gps"
 )
@@ -11,19 +11,40 @@ func main() {
 	println("GPS UART Example")
 	machine.UART1.Configure(machine.UARTConfig{BaudRate: 9600})
 	ublox := gps.NewUART(&machine.UART1)
-	parser := gps.Parser(ublox)
+	parser := gps.NewParser()
 	var fix gps.Fix
 	for {
-		fix = parser.NextFix()
+		s, err := ublox.NextSentence()
+		if err != nil {
+			println(err)
+			continue
+		}
+
+		fix, err = parser.Parse(s)
+		if err != nil {
+			println(err)
+			continue
+		}
 		if fix.Valid {
 			print(fix.Time.Format("15:04:05"))
-			print(", lat=", fmt.Sprintf("%f", fix.Latitude))
-			print(", long=", fmt.Sprintf("%f", fix.Longitude))
-			print(", altitude:=", fix.Altitude)
+			print(", lat=")
+			print(fix.Latitude)
+			print(", long=")
+			print(fix.Longitude)
+			print(", altitude=", fix.Altitude)
 			print(", satellites=", fix.Satellites)
+			if fix.Speed != 0 {
+				print(", speed=")
+				print(fix.Speed)
+			}
+			if fix.Heading != 0 {
+				print(", heading=")
+				print(fix.Heading)
+			}
 			println()
 		} else {
 			println("No fix")
 		}
+		time.Sleep(200 * time.Millisecond)
 	}
 }

examples/ili9341/basic/atsamd21.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	display = ili9341.NewSpi(
+	display = ili9341.NewSPI(
 		machine.SPI0,
 		machine.D0,
 		machine.D1,

examples/ili9341/basic/wioterminal.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	display = ili9341.NewSpi(
+	display = ili9341.NewSPI(
 		machine.SPI3,
 		machine.LCD_DC,
 		machine.LCD_SS_PIN,

examples/ili9341/pyportal_boing/wioterminal.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	display = ili9341.NewSpi(
+	display = ili9341.NewSPI(
 		machine.SPI3,
 		machine.LCD_DC,
 		machine.LCD_SS_PIN,

examples/ili9341/scroll/atsamd21.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	display = ili9341.NewSpi(
+	display = ili9341.NewSPI(
 		machine.SPI0,
 		machine.D0,
 		machine.D1,

examples/ili9341/scroll/wioterminal.go

@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	display = ili9341.NewSpi(
+	display = ili9341.NewSPI(
 		machine.SPI3,
 		machine.LCD_DC,
 		machine.LCD_SS_PIN,

examples/lis2mdl/main.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/lis2mdl"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{})
+	compass := lis2mdl.New(machine.I2C0)
+
+	if !compass.Connected() {
+		for {
+			println("LIS2MDL not connected!")
+			time.Sleep(1 * time.Second)
+		}
+	}
+
+	compass.Configure(lis2mdl.Configuration{}) //default settings
+
+	for {
+		heading := compass.ReadCompass()
+		println("Heading:", heading)
+
+		time.Sleep(time.Millisecond * 100)
+	}
+}

examples/st7789/main.go

@@ -9,12 +9,37 @@ import (
 )
 
 func main() {
+
+	// Example configuration for Adafruit Clue
+	// machine.SPI1.Configure(machine.SPIConfig{
+	//	Frequency: 8000000,
+	//	SCK:       machine.TFT_SCK,
+	//	SDO:       machine.TFT_SDO,
+	//	SDI:       machine.TFT_SDO,
+	//	Mode:      0,
+	// })
+	// display := st7789.New(machine.SPI1,
+	//	machine.TFT_RESET,
+	//	machine.TFT_DC,
+	//	machine.TFT_CS,
+	//	machine.TFT_LITE)
+
 	machine.SPI0.Configure(machine.SPIConfig{
 		Frequency: 8000000,
-		Mode:      3,
+		Mode:      0,
+	})
+	display := st7789.New(machine.SPI0,
+		machine.P6, // TFT_RESET
+		machine.P7, // TFT_DC
+		machine.P8, // TFT_CS
+		machine.P9) // TFT_LITE
+
+	display.Configure(st7789.Config{
+		Rotation:   st7789.NO_ROTATION,
+		RowOffset:  80,
+		FrameRate:  st7789.FRAMERATE_111,
+		VSyncLines: st7789.MAX_VSYNC_SCANLINES,
 	})
-	display := st7789.New(machine.SPI0, machine.P6, machine.P7, machine.P8)
-	display.Configure(st7789.Config{Rotation: st7789.NO_ROTATION})
 
 	width, height := display.Size()
 

examples/waveshare-epd/epd4in2/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"machine"
+
+	"image/color"
+
+	"time"
+
+	"tinygo.org/x/drivers/waveshare-epd/epd4in2"
+)
+
+var display epd4in2.Device
+
+func main() {
+	machine.SPI0.Configure(machine.SPIConfig{
+		Frequency: 8000000,
+		Mode:      0,
+	})
+
+	display = epd4in2.New(machine.SPI0, machine.P6, machine.P7, machine.P8, machine.P9)
+	display.Configure(epd4in2.Config{})
+
+	black := color.RGBA{1, 1, 1, 255}
+
+	display.ClearBuffer()
+	println("Clear the display")
+	display.ClearDisplay()
+	display.WaitUntilIdle()
+	println("Waiting for 2 seconds")
+	time.Sleep(2 * time.Second)
+
+	// Show a checkered board
+	for i := int16(0); i < 16; i++ {
+		for j := int16(0); j < 25; j++ {
+			if (i+j)%2 == 0 {
+				showRect(i*8, j*10, 8, 10, black)
+			}
+		}
+	}
+	println("Show checkered board")
+	display.Display()
+	display.WaitUntilIdle()
+	println("Waiting for 2 seconds")
+	time.Sleep(2 * time.Second)
+
+	println("You could remove power now")
+}
+
+func showRect(x int16, y int16, w int16, h int16, c color.RGBA) {
+	for i := x; i < x+w; i++ {
+		for j := y; j < y+h; j++ {
+			display.SetPixel(i, j, c)
+		}
+	}
+}

go.mod

@@ -1,5 +1,8 @@
 module tinygo.org/x/drivers
 
-go 1.14
+go 1.15
 
-require github.com/eclipse/paho.mqtt.golang v1.2.0
+require (
+	github.com/eclipse/paho.mqtt.golang v1.2.0
+	github.com/frankban/quicktest v1.10.2
+)

go.sum

@@ -1,2 +1,13 @@
 github.com/eclipse/paho.mqtt.golang v1.2.0 h1:1F8mhG9+aO5/xpdtFkW4SxOJB67ukuDC3t2y2qayIX0=
 github.com/eclipse/paho.mqtt.golang v1.2.0/go.mod h1:H9keYFcgq3Qr5OUJm/JZI/i6U7joQ8SYLhZwfeOo6Ts=
+github.com/frankban/quicktest v1.10.2 h1:19ARM85nVi4xH7xPXuc5eM/udya5ieh7b/Sv+d844Tk=
+github.com/frankban/quicktest v1.10.2/go.mod h1:K+q6oSqb0W0Ininfk863uOk1lMy69l/P6txr3mVT54s=
+github.com/google/go-cmp v0.5.2 h1:X2ev0eStA3AbceY54o37/0PQ/UWqKEiiO2dKL5OPaFM=
+github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
+github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

gps/gps.go

@@ -3,24 +3,32 @@ package gps // import "tinygo.org/x/drivers/gps"
 
 import (
 	"encoding/hex"
+	"errors"
 	"machine"
 	"strings"
 	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+var (
+	errInvalidNMEASentenceLength = errors.New("invalid NMEA sentence length")
+	errInvalidNMEAChecksum       = errors.New("invalid NMEA sentence checksum")
 )
 
 // Device wraps a connection to a GPS device.
-type GPSDevice struct {
+type Device struct {
 	buffer   []byte
 	bufIdx   int
 	sentence strings.Builder
 	uart     *machine.UART
-	bus      *machine.I2C
+	bus      drivers.I2C
 	address  uint16
 }
 
 // NewUART creates a new UART GPS connection. The UART must already be configured.
-func NewUART(uart *machine.UART) GPSDevice {
-	return GPSDevice{
+func NewUART(uart *machine.UART) Device {
+	return Device{
 		uart:     uart,
 		buffer:   make([]byte, bufferSize),
 		bufIdx:   bufferSize,
@@ -29,8 +37,8 @@ func NewUART(uart *machine.UART) GPSDevice {
 }
 
 // NewI2C creates a new I2C GPS connection.
-func NewI2C(bus *machine.I2C) GPSDevice {
-	return GPSDevice{
+func NewI2C(bus drivers.I2C) Device {
+	return Device{
 		bus:      bus,
 		address:  I2C_ADDRESS,
 		buffer:   make([]byte, bufferSize),
@@ -39,17 +47,17 @@ func NewI2C(bus *machine.I2C) GPSDevice {
 	}
 }
 
-// ReadNextSentence returns the next valid NMEA sentence from the GPS device.
-func (gps *GPSDevice) NextSentence() (sentence string) {
+// NextSentence returns the next valid NMEA sentence from the GPS device.
+func (gps *Device) NextSentence() (sentence string, err error) {
 	sentence = gps.readNextSentence()
-	for !validSentence(sentence) {
-		sentence = gps.readNextSentence()
+	if err = validSentence(sentence); err != nil {
+		return "", err
 	}
-	return sentence
+	return sentence, nil
 }
 
 // readNextSentence returns the next sentence from the GPS device.
-func (gps *GPSDevice) readNextSentence() (sentence string) {
+func (gps *Device) readNextSentence() (sentence string) {
 	gps.sentence.Reset()
 	var b byte = ' '
 
@@ -69,7 +77,7 @@ func (gps *GPSDevice) readNextSentence() (sentence string) {
 	return sentence
 }
 
-func (gps *GPSDevice) readNextByte() (b byte) {
+func (gps *Device) readNextByte() (b byte) {
 	gps.bufIdx += 1
 	if gps.bufIdx >= bufferSize {
 		gps.fillBuffer()
@@ -77,7 +85,7 @@ func (gps *GPSDevice) readNextByte() (b byte) {
 	return gps.buffer[gps.bufIdx]
 }
 
-func (gps *GPSDevice) fillBuffer() {
+func (gps *Device) fillBuffer() {
 	if gps.uart != nil {
 		gps.uartFillBuffer()
 	} else {
@@ -85,7 +93,7 @@ func (gps *GPSDevice) fillBuffer() {
 	}
 }
 
-func (gps *GPSDevice) uartFillBuffer() {
+func (gps *Device) uartFillBuffer() {
 	for gps.uart.Buffered() < bufferSize {
 		time.Sleep(100 * time.Millisecond)
 	}
@@ -93,7 +101,7 @@ func (gps *GPSDevice) uartFillBuffer() {
 	gps.bufIdx = 0
 }
 
-func (gps *GPSDevice) i2cFillBuffer() {
+func (gps *Device) i2cFillBuffer() {
 	for gps.available() < bufferSize {
 		time.Sleep(100 * time.Millisecond)
 	}
@@ -102,7 +110,7 @@ func (gps *GPSDevice) i2cFillBuffer() {
 }
 
 // Available returns how many bytes of GPS data are currently available.
-func (gps *GPSDevice) available() (available int) {
+func (gps *Device) available() (available int) {
 	var lengthBytes [2]byte
 	gps.bus.Tx(gps.address, []byte{BYTES_AVAIL_REG}, lengthBytes[0:2])
 	available = int(lengthBytes[0])*256 + int(lengthBytes[1])
@@ -110,7 +118,7 @@ func (gps *GPSDevice) available() (available int) {
 }
 
 // WriteBytes sends data/commands to the GPS device
-func (gps *GPSDevice) WriteBytes(bytes []byte) {
+func (gps *Device) WriteBytes(bytes []byte) {
 	if gps.uart != nil {
 		gps.uart.Write(bytes)
 	} else {
@@ -119,14 +127,18 @@ func (gps *GPSDevice) WriteBytes(bytes []byte) {
 }
 
 // validSentence checks if a sentence has been received uncorrupted
-func validSentence(sentence string) bool {
+func validSentence(sentence string) error {
 	if len(sentence) < 4 || sentence[0] != '$' || sentence[len(sentence)-3] != '*' {
-		return false
+		return errInvalidNMEASentenceLength
 	}
 	var cs byte = 0
 	for i := 1; i < len(sentence)-3; i++ {
 		cs ^= sentence[i]
 	}
 	checksum := hex.EncodeToString([]byte{cs})
-	return (checksum[0] == sentence[len(sentence)-2]) && (checksum[1] == sentence[len(sentence)-1])
+	if (checksum[0] != sentence[len(sentence)-2]) || (checksum[1] != sentence[len(sentence)-1]) {
+		return errInvalidNMEAChecksum
+	}
+
+	return nil
 }

gps/gpsparser.go

@@ -1,92 +1,131 @@
 package gps
 
 import (
+	"errors"
 	"strconv"
 	"strings"
 	"time"
 )
 
-type GPSParser struct {
-	gpsDevice GPSDevice
+var (
+	errEmptyNMEASentence   = errors.New("cannot parse empty NMEA sentence")
+	errUnknownNMEASentence = errors.New("unsupported NMEA sentence type")
+	errInvalidGGASentence  = errors.New("invalid GGA NMEA sentence")
+	errInvalidRMCSentence  = errors.New("invalid RMC NMEA sentence")
+)
+
+// Parser for GPS NMEA sentences.
+type Parser struct {
 }
 
-// fix is a GPS location fix
+// Fix is a GPS location fix
 type Fix struct {
-	Valid      bool
-	Time       time.Time
-	Latitude   float32
-	Longitude  float32
-	Altitude   int32
+	// Valid if the fix was valid.
+	Valid bool
+
+	// Time that the fix was taken, in UTC time.
+	Time time.Time
+
+	// Latitude is the decimal latitude. Negative numbers indicate S.
+	Latitude float32
+
+	// Longitude is the decimal longitude. Negative numbers indicate E.
+	Longitude float32
+
+	// Altitude is only returned for GGA sentences.
+	Altitude int32
+
+	// Satellites is the number of visible satellites, but is only returned for GGA sentences.
 	Satellites int16
+
+	// Speed based on reported movement. Only returned for RMC sentences.
+	Speed float32
+
+	// Heading based on reported movement. Only returned for RMC sentences.
+	Heading float32
 }
 
-func Parser(gpsDevice GPSDevice) GPSParser {
-	return GPSParser{
-		gpsDevice: gpsDevice,
+// NewParser returns a GPS NMEA Parser.
+func NewParser() Parser {
+	return Parser{}
+}
+
+// Parse parses a NMEA sentence looking for fix info.
+func (parser *Parser) Parse(sentence string) (fix Fix, err error) {
+	if sentence == "" {
+		err = errEmptyNMEASentence
+		return
 	}
-}
-
-// NextFix returns the next GPS location Fix from the GPS device
-func (parser *GPSParser) NextFix() (fix Fix) {
-	var ggaSentence = nextGGA(parser.gpsDevice)
-	var ggaFields = strings.Split(ggaSentence, ",")
-	fix.Altitude = findAltitude(ggaFields)
-	fix.Satellites = findSatellites(ggaFields)
-	fix.Longitude = findLongitude(ggaFields)
-	fix.Latitude = findLatitude(ggaFields)
-	fix.Time = findTime(ggaFields)
-	fix.Valid = (fix.Altitude != -99999) && (fix.Satellites > 0)
-	return fix
-}
-
-// nextGGA returns the next GGA type sentence from the GPS device
-// $--GGA,,,,,,,,,,,,,,*hh
-func nextGGA(gpsDevice GPSDevice) (sentence string) {
-	for {
-		sentence = gpsDevice.NextSentence()
-		if sentence[3:6] == "GGA" {
-			return sentence
+	typ := sentence[3:6]
+	switch typ {
+	case "GGA":
+		fields := strings.Split(sentence, ",")
+		if len(fields) != 15 {
+			err = errInvalidGGASentence
+			return
 		}
+
+		fix.Altitude = findAltitude(fields[9])
+		fix.Satellites = findSatellites(fields[7])
+		fix.Longitude = findLongitude(fields[4], fields[5])
+		fix.Latitude = findLatitude(fields[2], fields[3])
+		fix.Time = findTime(fields[1])
+		fix.Valid = (fix.Altitude != -99999) && (fix.Satellites > 0)
+	case "RMC":
+		fields := strings.Split(sentence, ",")
+		if len(fields) != 13 {
+			err = errInvalidRMCSentence
+			return
+		}
+
+		fix.Longitude = findLongitude(fields[5], fields[6])
+		fix.Latitude = findLatitude(fields[3], fields[4])
+		fix.Time = findTime(fields[1])
+		fix.Speed = findSpeed(fields[7])
+		fix.Heading = findHeading(fields[8])
+		fix.Valid = (len(fields[2]) > 0 && fields[2][0:1] == "A")
+	default:
+		err = errUnknownNMEASentence
 	}
+	return
 }
 
-// findTime returns the time from a GGA sentence:
+// findTime returns the time from an NMEA sentence:
 // $--GGA,hhmmss.ss,,,,,,,,,,,,,*xx
-func findTime(ggaFields []string) time.Time {
-	if len(ggaFields) < 1 || len(ggaFields[1]) < 6 {
+func findTime(val string) time.Time {
+	if len(val) < 6 {
 		return time.Time{}
 	}
-	ts := strings.Builder{}
-	ts.WriteString(ggaFields[1][0:2])
-	ts.WriteString(":")
-	ts.WriteString(ggaFields[1][2:4])
-	ts.WriteString(":")
-	ts.WriteString(ggaFields[1][4:6])
-	var t, _ = time.Parse("15:04:05", ts.String())
+
+	h, _ := strconv.ParseInt(val[0:2], 10, 8)
+	m, _ := strconv.ParseInt(val[2:4], 10, 8)
+	s, _ := strconv.ParseInt(val[4:6], 10, 8)
+	ms, _ := strconv.ParseInt(val[7:10], 10, 16)
+	t := time.Date(0, 0, 0, int(h), int(m), int(s), int(ms), time.UTC)
 
 	return t
 }
 
-// findAltitude returns the altitude from a GGA sentence:
+// findAltitude returns the altitude from an NMEA sentence:
 // $--GGA,,,,,,,,,25.8,,,,,*63
-func findAltitude(ggaFields []string) int32 {
-	if len(ggaFields) > 8 && len(ggaFields[9]) > 0 {
-		var v, _ = strconv.ParseFloat(ggaFields[9], 32)
+func findAltitude(val string) int32 {
+	if len(val) > 0 {
+		var v, _ = strconv.ParseFloat(val, 32)
 		return int32(v)
 	}
 	return -99999
 }
 
-// findLatitude returns the Latitude from a GGA sentence:
+// findLatitude returns the Latitude from an NMEA sentence:
 // $--GGA,,ddmm.mmmmm,x,,,,,,,,,,,*hh
-func findLatitude(ggaFields []string) float32 {
-	if len(ggaFields) > 2 && len(ggaFields[2]) > 8 {
-		var dd = ggaFields[2][0:2]
-		var mm = ggaFields[2][2:]
+func findLatitude(val, hemi string) float32 {
+	if len(val) > 8 {
+		var dd = val[0:2]
+		var mm = val[2:]
 		var d, _ = strconv.ParseFloat(dd, 32)
 		var m, _ = strconv.ParseFloat(mm, 32)
 		var v = float32(d + (m / 60))
-		if ggaFields[3] == "S" {
+		if hemi == "S" {
 			v *= -1
 		}
 		return v
@@ -94,16 +133,16 @@ func findLatitude(ggaFields []string) float32 {
 	return 0.0
 }
 
-// findLatitude returns the longitude from a GGA sentence:
+// findLatitude returns the longitude from an NMEA sentence:
 // $--GGA,,,,dddmm.mmmmm,x,,,,,,,,,*hh
-func findLongitude(ggaFields []string) float32 {
-	if len(ggaFields) > 4 && len(ggaFields[4]) > 8 {
-		var ddd = ggaFields[4][0:3]
-		var mm = ggaFields[4][3:]
+func findLongitude(val, hemi string) float32 {
+	if len(val) > 8 {
+		var ddd = val[0:3]
+		var mm = val[3:]
 		var d, _ = strconv.ParseFloat(ddd, 32)
 		var m, _ = strconv.ParseFloat(mm, 32)
 		var v = float32(d + (m / 60))
-		if ggaFields[5] == "W" {
+		if hemi == "W" {
 			v *= -1
 		}
 		return v
@@ -111,14 +150,32 @@ func findLongitude(ggaFields []string) float32 {
 	return 0.0
 }
 
-// findSatellites returns the satellites from a GGA sentence:
+// findSatellites returns the satellites from an NMEA sentence:
 // $--GGA,,,,,,,nn,,,,,,,*hh
-func findSatellites(ggaFields []string) (n int16) {
-	if len(ggaFields) > 6 && len(ggaFields[7]) > 0 {
-		var nn = ggaFields[7]
+func findSatellites(val string) (n int16) {
+	if len(val) > 0 {
+		var nn = val
 		var v, _ = strconv.ParseInt(nn, 10, 32)
 		n = int16(v)
 		return n
 	}
 	return 0
 }
+
+// findSpeed returns the speed from an RMC NMEA sentence.
+func findSpeed(val string) float32 {
+	if len(val) > 0 {
+		var v, _ = strconv.ParseFloat(val, 32)
+		return float32(v)
+	}
+	return 0
+}
+
+// findHeading returns the speed from an RMC NMEA sentence.
+func findHeading(val string) float32 {
+	if len(val) > 0 {
+		var v, _ = strconv.ParseFloat(val, 32)
+		return float32(v)
+	}
+	return 0
+}

gps/registers.go

@@ -13,5 +13,5 @@ const (
 )
 
 const (
-	bufferSize = 32
+	bufferSize = 100
 )

gps/ublox.go

@@ -24,25 +24,25 @@ var cfg_gnss_cmd = [...]byte{
 	0x01, 0x01, 0x06, 0x08, 0x0E, 0x00, 0x00, 0x00,
 	0x01, 0x01, 0xFC, 0x11}
 
-func FlightMode(gpsDevice GPSDevice) (err error) {
-	err = sendCommand(gpsDevice, flight_mode_cmd[:])
+func FlightMode(d Device) (err error) {
+	err = sendCommand(d, flight_mode_cmd[:])
 	return err
 }
 
-func SetCfgGNSS(gpsDevice GPSDevice) (err error) {
-	err = sendCommand(gpsDevice, cfg_gnss_cmd[:])
+func SetCfgGNSS(d Device) (err error) {
+	err = sendCommand(d, cfg_gnss_cmd[:])
 	return err
 }
 
-func sendCommand(gpsDevice GPSDevice, command []byte) (err error) {
-	gpsDevice.WriteBytes(command)
+func sendCommand(d Device, command []byte) (err error) {
+	d.WriteBytes(command)
 	start := time.Now()
 	for time.Now().Sub(start) < 1000 {
-		if gpsDevice.readNextByte() == '\n' {
-			if gpsDevice.readNextByte() == 0xB5 {
-				gpsDevice.readNextByte()
-				if gpsDevice.readNextByte() == 0x05 {
-					if gpsDevice.readNextByte() == 0x01 {
+		if d.readNextByte() == '\n' {
+			if d.readNextByte() == 0xB5 {
+				d.readNextByte()
+				if d.readNextByte() == 0x05 {
+					if d.readNextByte() == 0x01 {
 						return
 					}
 				}

hd44780i2c/hd44780i2c.go

@@ -7,13 +7,14 @@ package hd44780i2c
 
 import (
 	"errors"
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a HD44780 I2C LCD with related data.
 type Device struct {
-	bus             machine.I2C
+	bus             drivers.I2C
 	addr            uint8
 	width           uint8
 	height          uint8
@@ -41,7 +42,7 @@ type Config struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C, addr uint8) Device {
+func New(bus drivers.I2C, addr uint8) Device {
 	if addr == 0 {
 		addr = 0x27
 	}

i2c.go

@@ -0,0 +1,9 @@
+package drivers
+
+// I2C represents an I2C bus. It is notably implemented by the
+// machine.I2C type.
+type I2C interface {
+	ReadRegister(addr uint8, r uint8, buf []byte) error
+	WriteRegister(addr uint8, r uint8, buf []byte) error
+	Tx(addr uint16, w, r []byte) error
+}

ili9341/ili9341.go

@@ -20,7 +20,7 @@ type Device struct {
 	driver   driver
 
 	x0, x1 int16 // cached address window; prevents useless/expensive
-	y0, y1 int16 // syscalls to PASET, CASET, and RAMWR
+	y0, y1 int16 // syscalls to PASET and CASET
 
 	dc  machine.Pin
 	cs  machine.Pin
@@ -28,6 +28,7 @@ type Device struct {
 	rd  machine.Pin
 }
 
+// Configure prepares display for use
 func (d *Device) Configure(config Config) {
 
 	if config.Width == 0 {
@@ -145,6 +146,7 @@ func (d *Device) Display() error {
 	return nil
 }
 
+// DrawRGBBitmap copies an RGB bitmap to the internal buffer at given coordinates
 func (d *Device) DrawRGBBitmap(x, y int16, data []uint16, w, h int16) error {
 	k, i := d.Size()
 	if x < 0 || y < 0 || w <= 0 || h <= 0 ||
@@ -158,7 +160,7 @@ func (d *Device) DrawRGBBitmap(x, y int16, data []uint16, w, h int16) error {
 	return nil
 }
 
-// FillRectangle fills a rectangle at a given coordinates with a color
+// FillRectangle fills a rectangle at given coordinates with a color
 func (d *Device) FillRectangle(x, y, width, height int16, c color.RGBA) error {
 	k, i := d.Size()
 	if x < 0 || y < 0 || width <= 0 || height <= 0 ||
@@ -173,7 +175,7 @@ func (d *Device) FillRectangle(x, y, width, height int16, c color.RGBA) error {
 	return nil
 }
 
-// DrawRectangle fills a rectangle at a given coordinates with a color
+// DrawRectangle draws a rectangle at given coordinates with a color
 func (d *Device) DrawRectangle(x, y, w, h int16, c color.RGBA) error {
 	if err := d.DrawFastHLine(x, x+w-1, y, c); err != nil {
 		return err
@@ -215,6 +217,7 @@ func (d *Device) FillScreen(c color.RGBA) {
 	}
 }
 
+// GetRotation returns the current rotation of the device
 func (d *Device) GetRotation() Rotation {
 	return d.rotation
 }
@@ -236,7 +239,8 @@ func (d *Device) SetRotation(rotation Rotation) {
 	d.rotation = rotation
 }
 
-// SetScrollWindow sets an area to scroll with fixed top and bottom parts of the display
+// SetScrollArea sets an area to scroll with fixed top/bottom or left/right parts of the display
+// Rotation affects scroll direction
 func (d *Device) SetScrollArea(topFixedArea, bottomFixedArea int16) {
 	d.sendCommand(VSCRDEF, []uint8{
 		uint8(topFixedArea >> 8), uint8(topFixedArea),
@@ -251,7 +255,7 @@ func (d *Device) SetScroll(line int16) {
 	d.sendCommand(VSCRSADD, []uint8{uint8(line >> 8), uint8(line)})
 }
 
-// SpotScroll returns the display to its normal state
+// StopScroll returns the display to its normal state
 func (d *Device) StopScroll() {
 	d.sendCommand(NORON, nil)
 }
@@ -260,10 +264,8 @@ func (d *Device) StopScroll() {
 func (d *Device) setWindow(x, y, w, h int16) {
 	//x += d.columnOffset
 	//y += d.rowOffset
-	wr := false
 	x1 := x + w - 1
 	if x != d.x0 || x1 != d.x1 {
-		wr = true
 		d.sendCommand(CASET, []uint8{
 			uint8(x >> 8), uint8(x), uint8(x1 >> 8), uint8(x1),
 		})
@@ -271,15 +273,12 @@ func (d *Device) setWindow(x, y, w, h int16) {
 	}
 	y1 := y + h - 1
 	if y != d.y0 || y1 != d.y1 {
-		wr = true
 		d.sendCommand(PASET, []uint8{
 			uint8(y >> 8), uint8(y), uint8(y1 >> 8), uint8(y1),
 		})
 		d.y0, d.y1 = y, y1
 	}
-	if wr {
-		d.sendCommand(RAMWR, nil)
-	}
+	d.sendCommand(RAMWR, nil)
 }
 
 //go:inline

ili9341/spi_atsamd21.go

@@ -11,7 +11,7 @@ type spiDriver struct {
 	bus machine.SPI
 }
 
-func NewSpi(bus machine.SPI, dc, cs, rst machine.Pin) *Device {
+func NewSPI(bus machine.SPI, dc, cs, rst machine.Pin) *Device {
 	return &Device{
 		dc:  dc,
 		cs:  cs,

ili9341/spi_atsamd51.go

@@ -11,7 +11,7 @@ type spiDriver struct {
 	bus machine.SPI
 }
 
-func NewSpi(bus machine.SPI, dc, cs, rst machine.Pin) *Device {
+func NewSPI(bus machine.SPI, dc, cs, rst machine.Pin) *Device {
 	return &Device{
 		dc:  dc,
 		cs:  cs,

lis2mdl/lis2mdl.go

@@ -0,0 +1,126 @@
+// Package lis2mdl implements a driver for the LIS2MDL,
+// a magnetic sensor which is included on BBC micro:bit v1.5.
+//
+// Datasheet: https://www.st.com/resource/en/datasheet/lis2mdl.pdf
+//
+package lis2mdl // import "tinygo.org/x/drivers/lis2mdl"
+
+import (
+	"math"
+	"time"
+
+	"tinygo.org/x/drivers"
+)
+
+// Device wraps an I2C connection to a LIS2MDL device.
+type Device struct {
+	bus        drivers.I2C
+	Address    uint8
+	PowerMode  uint8
+	SystemMode uint8
+	DataRate   uint8
+}
+
+// Configuration for LIS2MDL device.
+type Configuration struct {
+	PowerMode  uint8
+	SystemMode uint8
+	DataRate   uint8
+}
+
+// New creates a new LIS2MDL connection. The I2C bus must already be
+// configured.
+//
+// This function only creates the Device object, it does not touch the device.
+func New(bus drivers.I2C) Device {
+	return Device{bus: bus, Address: ADDRESS}
+}
+
+// Connected returns whether LIS2MDL sensor has been found.
+func (d *Device) Connected() bool {
+	data := []byte{0}
+	d.bus.ReadRegister(uint8(d.Address), WHO_AM_I, data)
+	return data[0] == 0x40
+}
+
+// Configure sets up the LIS2MDL device for communication.
+func (d *Device) Configure(cfg Configuration) {
+	if cfg.PowerMode != 0 {
+		d.PowerMode = cfg.PowerMode
+	} else {
+		d.PowerMode = POWER_NORMAL
+	}
+
+	if cfg.DataRate != 0 {
+		d.DataRate = cfg.DataRate
+	} else {
+		d.DataRate = DATARATE_100HZ
+	}
+
+	if cfg.SystemMode != 0 {
+		d.SystemMode = cfg.SystemMode
+	} else {
+		d.SystemMode = SYSTEM_CONTINUOUS
+	}
+
+	cmd := []byte{0}
+
+	// reset
+	cmd[0] = byte(1 << 5)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_A, cmd)
+	time.Sleep(100 * time.Millisecond)
+
+	// reboot
+	cmd[0] = byte(1 << 6)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_A, cmd)
+	time.Sleep(100 * time.Millisecond)
+
+	// bdu
+	cmd[0] = byte(1 << 4)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_C, cmd)
+
+	// Temperature compensation is on for magnetic sensor (0x80)
+	cmd[0] = byte(0x80)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_A, cmd)
+
+	// speed
+	cmd[0] = byte(0x80 | d.DataRate)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_A, cmd)
+}
+
+// ReadMagneticField reads the current magnetic field from the device and returns
+// it in mG (milligauss). 1 mG = 0.1 µT (microtesla).
+func (d *Device) ReadMagneticField() (x int32, y int32, z int32) {
+	// turn back on read mode, even though it is supposed to be continuous?
+	cmd := []byte{0}
+	cmd[0] = byte(0x80 | d.PowerMode<<4 | d.DataRate<<2 | d.SystemMode)
+	d.bus.WriteRegister(uint8(d.Address), CFG_REG_A, cmd)
+	time.Sleep(10 * time.Millisecond)
+
+	data := make([]byte, 6)
+	d.bus.ReadRegister(uint8(d.Address), OUTX_L_REG, data)
+
+	x = int32(int16((uint16(data[0]) << 8) | uint16(data[1])))
+	y = int32(int16((uint16(data[2]) << 8) | uint16(data[3])))
+	z = int32(int16((uint16(data[4]) << 8) | uint16(data[5])))
+
+	return
+}
+
+// ReadCompass reads the current compass heading from the device and returns
+// it in degrees. When the z axis is pointing straight to Earth and
+// the y axis is pointing to North, the heading would be zero.
+//
+// However, the heading may be off due to electronic compasses would be effected
+// by strong magnetic fields and require constant calibration.
+func (d *Device) ReadCompass() (h int32) {
+	x, y, _ := d.ReadMagneticField()
+	xf, yf := float64(x)*0.15, float64(y)*0.15
+
+	rh := (math.Atan2(yf, xf) * 180) / math.Pi
+	if rh < 0 {
+		rh = 360 + rh
+	}
+
+	return int32(rh)
+}

lis2mdl/lis2mdl_test.go

@@ -0,0 +1,59 @@
+package lis2mdl
+
+import (
+	"testing"
+
+	qt "github.com/frankban/quicktest"
+	"tinygo.org/x/drivers/tester"
+)
+
+func TestDefaultI2CAddress(t *testing.T) {
+	c := qt.New(t)
+	bus := tester.NewI2CBus(c)
+	dev := New(bus)
+	c.Assert(dev.Address, qt.Equals, uint8(ADDRESS))
+}
+
+func TestWhoAmI(t *testing.T) {
+	c := qt.New(t)
+	bus := tester.NewI2CBus(c)
+	fake := tester.NewI2CDevice(c, ADDRESS)
+	fake.SetupRegisters(defaultRegisters())
+	bus.AddDevice(fake)
+
+	dev := New(bus)
+	c.Assert(dev.Connected(), qt.Equals, true)
+
+	fake.SetupRegister(WHO_AM_I, 0x99)
+	c.Assert(dev.Connected(), qt.Equals, false)
+}
+
+// defaultRegisters returns the default values for all of the device's registers.
+// see table 22 on page 27 of the datasheet.
+func defaultRegisters() []uint8 {
+	return []uint8{
+		OFFSET_X_REG_L: 0,
+		OFFSET_X_REG_H: 0,
+		OFFSET_Y_REG_L: 0,
+		OFFSET_Y_REG_H: 0,
+		OFFSET_Z_REG_L: 0,
+		OFFSET_Z_REG_H: 0,
+		WHO_AM_I:       0x40,
+		CFG_REG_A:      0x03,
+		CFG_REG_B:      0,
+		CFG_REG_C:      0,
+		INT_CRTL_REG:   0xE0,
+		INT_SOURCE_REG: 0,
+		INT_THS_L_REG:  0,
+		INT_THS_H_REG:  0,
+		STATUS_REG:     0,
+		OUTX_L_REG:     0,
+		OUTX_H_REG:     0,
+		OUTY_L_REG:     0,
+		OUTY_H_REG:     0,
+		OUTZ_L_REG:     0,
+		OUTZ_H_REG:     0,
+		TEMP_OUT_L_REG: 0,
+		TEMP_OUT_H_REG: 0,
+	}
+}

lis2mdl/registers.go

@@ -0,0 +1,45 @@
+package lis2mdl
+
+const (
+	// Constants/addresses used for I2C.
+	ADDRESS = 0x1E
+
+	// magnetic sensor registers.
+	OFFSET_X_REG_L = 0x45
+	OFFSET_X_REG_H = 0x46
+	OFFSET_Y_REG_L = 0x47
+	OFFSET_Y_REG_H = 0x48
+	OFFSET_Z_REG_L = 0x49
+	OFFSET_Z_REG_H = 0x4A
+	WHO_AM_I       = 0x4F
+	CFG_REG_A      = 0x60
+	CFG_REG_B      = 0x61
+	CFG_REG_C      = 0x62
+	INT_CRTL_REG   = 0x63
+	INT_SOURCE_REG = 0x64
+	INT_THS_L_REG  = 0x65
+	INT_THS_H_REG  = 0x66
+	STATUS_REG     = 0x67
+	OUTX_L_REG     = 0x68
+	OUTX_H_REG     = 0x69
+	OUTY_L_REG     = 0x6A
+	OUTY_H_REG     = 0x6B
+	OUTZ_L_REG     = 0x6C
+	OUTZ_H_REG     = 0x6D
+	TEMP_OUT_L_REG = 0x6E
+	TEMP_OUT_H_REG = 0x6F
+
+	// magnetic sensor power mode.
+	POWER_NORMAL = 0x00 // default
+	POWER_LOW    = 0x01
+
+	// magnetic sensor operate mode.
+	SYSTEM_CONTINUOUS = 0x00 // default
+	SYSTEM_SINGLE     = 0x01
+
+	// magnetic sensor data rate
+	DATARATE_10HZ  = 0x00 // default
+	DATARATE_20HZ  = 0x01
+	DATARATE_50HZ  = 0x02
+	DATARATE_100HZ = 0x03
+)

lis3dh/lis3dh.go

@@ -4,13 +4,11 @@
 //
 package lis3dh // import "tinygo.org/x/drivers/lis3dh"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device wraps an I2C connection to a LIS3DH device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 	r       Range
 }
@@ -18,7 +16,7 @@ type Device struct {
 // New creates a new LIS3DH connection. The I2C bus must already be configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus: bus, Address: Address0}
 }
 

lsm303agr/lsm303agr.go

@@ -6,13 +6,14 @@
 package lsm303agr // import "tinygo.org/x/drivers/lsm303agr"
 
 import (
-	"machine"
 	"math"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a LSM303AGR device.
 type Device struct {
-	bus            machine.I2C
+	bus            drivers.I2C
 	AccelAddress   uint8
 	MagAddress     uint8
 	AccelPowerMode uint8
@@ -37,7 +38,7 @@ type Configuration struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus: bus, AccelAddress: ACCEL_ADDRESS, MagAddress: MAG_ADDRESS}
 }
 

lsm6ds3/lsm6ds3.go

@@ -5,9 +5,7 @@
 //
 package lsm6ds3 // import "tinygo.org/x/drivers/lsm6ds3"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 type AccelRange uint8
 type AccelSampleRate uint8
@@ -18,7 +16,7 @@ type GyroSampleRate uint8
 
 // Device wraps an I2C connection to a LSM6DS3 device.
 type Device struct {
-	bus             machine.I2C
+	bus             drivers.I2C
 	Address         uint16
 	accelRange      AccelRange
 	accelSampleRate AccelSampleRate
@@ -44,7 +42,7 @@ type Configuration struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus: bus, Address: Address}
 }
 

mag3110/mag3110.go

@@ -5,13 +5,11 @@
 //
 package mag3110 // import "tinygo.org/x/drivers/mag3110"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device wraps an I2C connection to a MAG3110 device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 }
 
@@ -19,7 +17,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus, Address}
 }
 

mma8653/mma8653.go

@@ -6,13 +6,11 @@
 //
 package mma8653 // import "tinygo.org/x/drivers/mma8653"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device wraps an I2C connection to a MMA8653 device.
 type Device struct {
-	bus         machine.I2C
+	bus         drivers.I2C
 	Address     uint16
 	sensitivity Sensitivity
 }
@@ -21,7 +19,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus, Address, Sensitivity2G}
 }
 

mpu6050/mpu6050.go

@@ -7,13 +7,11 @@
 //
 package mpu6050 // import "tinygo.org/x/drivers/mpu6050"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device wraps an I2C connection to a MPU6050 device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 }
 
@@ -21,7 +19,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{bus, Address}
 }
 

sht3x/sht3x.go

@@ -7,13 +7,14 @@
 package sht3x // import "tinygo.org/x/drivers/sht3x"
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a SHT31 device.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	Address uint16
 }
 
@@ -22,7 +23,7 @@ type Device struct {
 //
 // This function only creates the Device object, it does not initialize the device.
 // You must call Configure() first in order to use the device itself.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: AddressA,

ssd1306/ssd1306.go

@@ -9,6 +9,8 @@ import (
 	"image/color"
 	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an SPI connection.
@@ -30,7 +32,7 @@ type Config struct {
 }
 
 type I2CBus struct {
-	wire    machine.I2C
+	wire    drivers.I2C
 	Address uint16
 }
 
@@ -50,7 +52,7 @@ type Buser interface {
 type VccMode uint8
 
 // NewI2C creates a new SSD1306 connection. The I2C wire must already be configured.
-func NewI2C(bus machine.I2C) Device {
+func NewI2C(bus drivers.I2C) Device {
 	return Device{
 		bus: &I2CBus{
 			wire:    bus,

st7789/registers.go

@@ -33,7 +33,9 @@ const (
 	RDID3      = 0xDC
 	RDID4      = 0xDD
 	FRMCTR1    = 0xB1
+	RGBCTRL    = 0xB1
 	FRMCTR2    = 0xB2
+	PORCTRL    = 0xB2
 	FRMCTR3    = 0xB3
 	INVCTR     = 0xB4
 	DISSET5    = 0xB6
@@ -43,12 +45,49 @@ const (
 	PWCTR4     = 0xC3
 	PWCTR5     = 0xC4
 	VMCTR1     = 0xC5
+	FRCTRL2    = 0xC6
 	PWCTR6     = 0xFC
 	GMCTRP1    = 0xE0
 	GMCTRN1    = 0xE1
+	GSCAN      = 0x45
 
 	NO_ROTATION  Rotation = 0
 	ROTATION_90  Rotation = 1 // 90 degrees clock-wise rotation
 	ROTATION_180 Rotation = 2
 	ROTATION_270 Rotation = 3
+
+	// Allowable frame rate codes for FRCTRL2 (Identifier is in Hz)
+	FRAMERATE_111 FrameRate = 0x01
+	FRAMERATE_105 FrameRate = 0x02
+	FRAMERATE_99  FrameRate = 0x03
+	FRAMERATE_94  FrameRate = 0x04
+	FRAMERATE_90  FrameRate = 0x05
+	FRAMERATE_86  FrameRate = 0x06
+	FRAMERATE_82  FrameRate = 0x07
+	FRAMERATE_78  FrameRate = 0x08
+	FRAMERATE_75  FrameRate = 0x09
+	FRAMERATE_72  FrameRate = 0x0A
+	FRAMERATE_69  FrameRate = 0x0B
+	FRAMERATE_67  FrameRate = 0x0C
+	FRAMERATE_64  FrameRate = 0x0D
+	FRAMERATE_62  FrameRate = 0x0E
+	FRAMERATE_60  FrameRate = 0x0F // 60 is default
+	FRAMERATE_58  FrameRate = 0x10
+	FRAMERATE_57  FrameRate = 0x11
+	FRAMERATE_55  FrameRate = 0x12
+	FRAMERATE_53  FrameRate = 0x13
+	FRAMERATE_52  FrameRate = 0x14
+	FRAMERATE_50  FrameRate = 0x15
+	FRAMERATE_49  FrameRate = 0x16
+	FRAMERATE_48  FrameRate = 0x17
+	FRAMERATE_46  FrameRate = 0x18
+	FRAMERATE_45  FrameRate = 0x19
+	FRAMERATE_44  FrameRate = 0x1A
+	FRAMERATE_43  FrameRate = 0x1B
+	FRAMERATE_42  FrameRate = 0x1C
+	FRAMERATE_41  FrameRate = 0x1D
+	FRAMERATE_40  FrameRate = 0x1E
+	FRAMERATE_39  FrameRate = 0x1F
+
+	MAX_VSYNC_SCANLINES = 254
 )

st7789/st7789.go

@@ -1,12 +1,14 @@
 // Package st7789 implements a driver for the ST7789 TFT displays, it comes in various screen sizes.
 //
-// Datasheet: https://cdn-shop.adafruit.com/product-files/3787/3787_tft_QT154H2201__________20190228182902.pdf
+// Datasheets: https://cdn-shop.adafruit.com/product-files/3787/3787_tft_QT154H2201__________20190228182902.pdf
+//             http://www.newhavendisplay.com/appnotes/datasheets/LCDs/ST7789V.pdf
 //
 package st7789 // import "tinygo.org/x/drivers/st7789"
 
 import (
 	"image/color"
 	"machine"
+	"math"
 	"time"
 
 	"errors"
@@ -14,11 +16,14 @@ import (
 
 type Rotation uint8
 
+type FrameRate uint8
+
 // Device wraps an SPI connection.
 type Device struct {
 	bus             machine.SPI
 	dcPin           machine.Pin
 	resetPin        machine.Pin
+	csPin           machine.Pin
 	blPin           machine.Pin
 	width           int16
 	height          int16
@@ -27,8 +32,10 @@ type Device struct {
 	columnOffset    int16
 	rowOffset       int16
 	rotation        Rotation
+	frameRate       FrameRate
 	batchLength     int32
 	isBGR           bool
+	vSyncLines      int16
 }
 
 // Config is the configuration for the display
@@ -38,17 +45,21 @@ type Config struct {
 	Rotation     Rotation
 	RowOffset    int16
 	ColumnOffset int16
+	FrameRate    FrameRate
+	VSyncLines   int16
 }
 
 // New creates a new ST7789 connection. The SPI wire must already be configured.
-func New(bus machine.SPI, resetPin, dcPin, blPin machine.Pin) Device {
+func New(bus machine.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})
 	blPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
 	return Device{
 		bus:      bus,
 		dcPin:    dcPin,
 		resetPin: resetPin,
+		csPin:    csPin,
 		blPin:    blPin,
 	}
 }
@@ -65,42 +76,149 @@ func (d *Device) Configure(cfg Config) {
 	} else {
 		d.height = 240
 	}
+
 	d.rotation = cfg.Rotation
 	d.rowOffsetCfg = cfg.RowOffset
 	d.columnOffsetCfg = cfg.ColumnOffset
 
+	if cfg.FrameRate != 0 {
+		d.frameRate = cfg.FrameRate
+	} else {
+		d.frameRate = FRAMERATE_60
+	}
+
+	if cfg.VSyncLines >= 2 && cfg.VSyncLines <= 254 {
+		d.vSyncLines = cfg.VSyncLines
+	} else {
+		d.vSyncLines = 16
+	}
+
 	d.batchLength = int32(d.width)
 	if d.height > d.width {
 		d.batchLength = int32(d.height)
 	}
 	d.batchLength += d.batchLength & 1
 
-	// reset the device
+	// Reset the device
 	d.resetPin.High()
-	time.Sleep(5 * time.Millisecond)
+	time.Sleep(50 * time.Millisecond)
 	d.resetPin.Low()
-	time.Sleep(20 * time.Millisecond)
+	time.Sleep(50 * time.Millisecond)
 	d.resetPin.High()
-	time.Sleep(150 * time.Millisecond)
+	time.Sleep(50 * time.Millisecond)
 
 	// Common initialization
-	d.Command(SWRESET)
-	time.Sleep(150 * time.Millisecond)
-	d.Command(SLPOUT)
-	time.Sleep(500 * time.Millisecond)
-	d.Command(COLMOD)
-	d.Data(0x55)
-	time.Sleep(10 * time.Millisecond)
+	d.Command(SWRESET)                 // Soft reset
+	time.Sleep(150 * time.Millisecond) //
 
-	d.SetRotation(d.rotation)
-	d.InvertColors(true)
+	d.Command(SLPOUT)                  // Exit sleep mode
+	time.Sleep(500 * time.Millisecond) //
 
-	d.Command(NORON)
-	time.Sleep(10 * time.Millisecond)
-	d.Command(DISPON)
-	time.Sleep(500 * time.Millisecond)
+	// Memory initialization
+	d.Command(COLMOD)                 // Set color mode
+	d.Data(0x55)                      //   16-bit color
+	time.Sleep(10 * time.Millisecond) //
 
-	d.blPin.High()
+	d.SetRotation(d.rotation) // Memory orientation
+
+	d.setWindow(0, 0, d.width, d.height)   // Full draw window
+	d.FillScreen(color.RGBA{0, 0, 0, 255}) // Clear screen
+
+	// Framerate
+	d.Command(FRCTRL2)         // Frame rate for normal mode
+	d.Data(uint8(d.frameRate)) // Default is 60Hz
+
+	// Frame vertical sync and "porch"
+	//
+	// Front and back porch controls vertical scanline sync time before and after
+	// a frame, where memory can be safely written without tearing.
+	//
+	fp := uint8(d.vSyncLines / 2)         // Split the desired pause half and half
+	bp := uint8(d.vSyncLines - int16(fp)) // between front and back porch.
+
+	d.Command(PORCTRL)
+	d.Data(bp)   // Back porch 5bit     (0x7F max 0x08 default)
+	d.Data(fp)   // Front porch 5bit    (0x7F max 0x08 default)
+	d.Data(0x00) // Seprarate porch     (TODO: what is this?)
+	d.Data(0x22) // Idle mode porch     (4bit-back 4bit-front 0x22 default)
+	d.Data(0x22) // Partial mode porch  (4bit-back 4bit-front 0x22 default)
+
+	// Ready to display
+	d.Command(INVON)                  // Inversion ON
+	time.Sleep(10 * time.Millisecond) //
+
+	d.Command(NORON)                  // Normal mode ON
+	time.Sleep(10 * time.Millisecond) //
+
+	d.Command(DISPON)                 // Screen ON
+	time.Sleep(10 * time.Millisecond) //
+
+	d.blPin.High() // Backlight ON
+}
+
+// Sync waits for the display to hit the next VSYNC pause
+func (d *Device) Sync() {
+	d.SyncToScanLine(0)
+}
+
+// SyncToScanLine waits for the display to hit a specific scanline
+//
+// A scanline value of 0 will forward to the beginning of the next VSYNC,
+// even if the display is currently in a VSYNC pause.
+//
+// Syncline values appear to increment once for every two vertical
+// lines on the display.
+//
+// NOTE: Use GetHighestScanLine and GetLowestScanLine to obtain the highest
+// and lowest useful values. Values are affected by front and back porch
+// vsync settings (derived from VSyncLines configuration option).
+//
+func (d *Device) SyncToScanLine(scanline uint16) {
+	scan := d.GetScanLine()
+
+	// Sometimes GetScanLine returns erroneous 0 on first call after draw, so double check
+	if scan == 0 {
+		scan = d.GetScanLine()
+	}
+
+	if scanline == 0 {
+		// we dont know where we are in an ongoing vsync so go around
+		for scan < 1 {
+			time.Sleep(1 * time.Millisecond)
+			scan = d.GetScanLine()
+		}
+		for scan > 0 {
+			scan = d.GetScanLine()
+		}
+	} else {
+		// go around unless we're very close to the target
+		for scan > scanline+4 {
+			time.Sleep(1 * time.Millisecond)
+			scan = d.GetScanLine()
+		}
+		for scan < scanline {
+			scan = d.GetScanLine()
+		}
+	}
+}
+
+// GetScanLine reads the current scanline value from the display
+func (d *Device) GetScanLine() uint16 {
+	data := []uint8{0x00, 0x00}
+	d.Rx(GSCAN, data)
+	return uint16(data[0])<<8 + uint16(data[1])
+}
+
+// GetHighestScanLine calculates the last scanline id in the frame before VSYNC pause
+func (d *Device) GetHighestScanLine() uint16 {
+	// Last scanline id appears to be backporch/2 + 320/2
+	return uint16(math.Ceil(float64(d.vSyncLines)/2)/2) + 160
+}
+
+// GetLowestScanLine calculate the first scanline id to appear after VSYNC pause
+func (d *Device) GetLowestScanLine() uint16 {
+	// First scanline id appears to be backporch/2 + 1
+	return uint16(math.Ceil(float64(d.vSyncLines)/2)/2) + 1
 }
 
 // Display does nothing, there's no buffer as it might be too big for some boards
@@ -123,7 +241,7 @@ func (d *Device) setWindow(x, y, w, h int16) {
 	x += d.columnOffset
 	y += d.rowOffset
 	d.Tx([]uint8{CASET}, true)
-	d.Tx([]uint8{uint8(x << 8), uint8(x), uint8((x + w - 1) >> 8), uint8(x + w - 1)}, false)
+	d.Tx([]uint8{uint8(x >> 8), uint8(x), uint8((x + w - 1) >> 8), uint8(x + w - 1)}, false)
 	d.Tx([]uint8{RASET}, true)
 	d.Tx([]uint8{uint8(y >> 8), uint8(y), uint8((y + h - 1) >> 8), uint8(y + h - 1)}, false)
 	d.Command(RAMWR)
@@ -158,6 +276,7 @@ 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()
@@ -248,7 +367,6 @@ func (d *Device) SetRotation(rotation Rotation) {
 	}
 	d.Command(MADCTL)
 	d.Data(madctl)
-
 }
 
 // Command sends a command to the display
@@ -265,11 +383,24 @@ func (d *Device) Data(data uint8) {
 func (d *Device) Tx(data []byte, isCommand bool) {
 	if isCommand {
 		d.dcPin.Low()
-		d.bus.Tx(data, nil)
 	} else {
 		d.dcPin.High()
-		d.bus.Tx(data, nil)
 	}
+	d.csPin.Low()
+	d.bus.Tx(data, nil)
+	d.csPin.High()
+}
+
+// Rx reads data from the display
+func (d *Device) Rx(command uint8, read_bytes []byte) {
+	d.dcPin.Low()
+	d.csPin.Low()
+	d.bus.Transfer(command)
+	d.dcPin.High()
+	for i := range read_bytes {
+		read_bytes[i], _ = d.bus.Transfer(0xFF)
+	}
+	d.csPin.High()
 }
 
 // Size returns the current size of the display.

tester/device.go

@@ -0,0 +1,83 @@
+package tester
+
+// MaxRegisters is the maximum number of registers supported for a Device.
+const MaxRegisters = 200
+
+// I2CDevice represents a mock I2C device on a mock I2C bus.
+type I2CDevice struct {
+	c Failer
+	// addr is the i2c device address.
+	addr uint8
+	// Registers holds the device registers. It can be inspected
+	// or changed as desired for testing.
+	registers [MaxRegisters]uint8
+	// If Err is non-nil, it will be returned as the error from the
+	// I2C methods.
+	Err error
+}
+
+// NewI2CDevice returns a new mock I2C device.
+func NewI2CDevice(c Failer, addr uint8) *I2CDevice {
+	return &I2CDevice{
+		c:    c,
+		addr: addr,
+	}
+}
+
+// Addr returns the Device address.
+func (d *I2CDevice) Addr() uint8 {
+	return d.addr
+}
+
+// SetupRegisters sets all of the Device registers.
+// It is intended to be used when setting up a fake device
+// for testing expected vs. actual values.
+func (d *I2CDevice) SetupRegisters(regs []uint8) {
+	if len(regs) > MaxRegisters {
+		panic("exceeded maximum number of registers for fake device")
+	}
+	for k, v := range regs {
+		d.registers[k] = v
+	}
+}
+
+// SetupRegister sets one of the Device registers.
+// It is intended to be used when setting up a fake device
+// for testing expected vs. actual values.
+func (d *I2CDevice) SetupRegister(r, v uint8) {
+	if r > MaxRegisters {
+		panic("exceeded maximum number of registers for fake device")
+	}
+	d.registers[r] = v
+}
+
+// ReadRegister implements I2C.ReadRegister.
+func (d *I2CDevice) ReadRegister(r uint8, buf []byte) error {
+	if d.Err != nil {
+		return d.Err
+	}
+	d.AssertRegisterRange(r, buf)
+	copy(buf, d.registers[r:])
+	return nil
+}
+
+// WriteRegister implements I2C.WriteRegister.
+func (d *I2CDevice) WriteRegister(r uint8, buf []byte) error {
+	if d.Err != nil {
+		return d.Err
+	}
+	d.AssertRegisterRange(r, buf)
+	copy(d.registers[r:], buf)
+	return nil
+}
+
+// AssertRegisterRange asserts that reading or writing the given
+// register and subsequent registers is in range of the available registers.
+func (d *I2CDevice) AssertRegisterRange(r uint8, buf []byte) {
+	if int(r) >= len(d.registers) {
+		d.c.Fatalf("register read/write [%#x, %#x] start out of range", r, int(r)+len(buf))
+	}
+	if int(r)+len(buf) > len(d.registers) {
+		d.c.Fatalf("register read/write [%#x, %#x] end out of range", r, int(r)+len(buf))
+	}
+}

tester/i2c.go

@@ -0,0 +1,48 @@
+package tester
+
+// I2CBus implements the I2C interface in memory for testing.
+type I2CBus struct {
+	c       Failer
+	devices []*I2CDevice
+}
+
+// NewI2CBus returns an I2CBus mock I2C instance that uses c to flag errors
+// if they happen. After creating a I2C instance, add devices
+// to it with addDevice before using NewI2CBus interface.
+func NewI2CBus(c Failer) *I2CBus {
+	return &I2CBus{
+		c: c,
+	}
+}
+
+// AddDevice adds a new mock device to the mock I2C bus.
+func (bus *I2CBus) AddDevice(d *I2CDevice) {
+	bus.devices = append(bus.devices, d)
+}
+
+// ReadRegister implements I2C.ReadRegister.
+func (bus *I2CBus) ReadRegister(addr uint8, r uint8, buf []byte) error {
+	return bus.FindDevice(addr).ReadRegister(r, buf)
+}
+
+// WriteRegister implements I2C.WriteRegister.
+func (bus *I2CBus) WriteRegister(addr uint8, r uint8, buf []byte) error {
+	return bus.FindDevice(addr).WriteRegister(r, buf)
+}
+
+// Tx implements I2C.Tx.
+func (bus *I2CBus) Tx(addr uint16, w, r []byte) error {
+	// TODO: implement this
+	return nil
+}
+
+// FindDevice returns the device with the given address.
+func (bus *I2CBus) FindDevice(addr uint8) *I2CDevice {
+	for _, dev := range bus.devices {
+		if dev.Addr() == addr {
+			return dev
+		}
+	}
+	bus.c.Fatalf("invalid device addr %#x passed to i2c bus", addr)
+	panic("unreachable")
+}

tester/tester.go

@@ -0,0 +1,13 @@
+// Package tester contains mock structs to make it easier to test I2C devices.
+//
+// TODO: info on how to use this.
+//
+package tester // import "tinygo.org/x/drivers/tester"
+
+// Failer is used by the I2CDevice type to abort when it's used in
+// unexpected ways, such as reading an out-of-range register.
+type Failer interface {
+	// Fatalf prints the Printf-formatted message and exits the current
+	// goroutine.
+	Fatalf(f string, a ...interface{})
+}

tmp102/tmp102.go

@@ -4,13 +4,11 @@
 
 package tmp102 // import "tinygo.org/x/drivers/tmp102"
 
-import (
-	"machine"
-)
+import "tinygo.org/x/drivers"
 
 // Device holds the already configured I2C bus and the address of the sensor.
 type Device struct {
-	bus     machine.I2C
+	bus     drivers.I2C
 	address uint8
 }
 
@@ -20,7 +18,7 @@ type Config struct {
 }
 
 // New creates a new TMP102 connection. The I2C bus must already be configured.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus: bus,
 	}

veml6070/veml6070.go

@@ -11,12 +11,12 @@ package veml6070 // import "tinygo.org/x/drivers/veml6070"
 import (
 	"time"
 
-	"machine"
+	"tinygo.org/x/drivers"
 )
 
 // Device wraps an I2C connection to a VEML6070 device.
 type Device struct {
-	bus         machine.I2C
+	bus         drivers.I2C
 	AddressLow  uint16
 	AddressHigh uint16
 	RSET        uint32
@@ -28,7 +28,7 @@ type Device struct {
 //
 // This function only creates the Device object, it does not initialize the device.
 // You must call Configure() first in order to use the device itself.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:         bus,
 		AddressLow:  ADDR_L,
@@ -119,7 +119,7 @@ func (d *Device) enable() error {
 
 func (d *Device) readData(address uint16) (byte, error) {
 	data := []byte{0}
-	err := machine.I2C0.Tx(address, []byte{}, data)
+	err := d.bus.Tx(address, []byte{}, data)
 	return data[0], err
 }
 

version.go

@@ -2,4 +2,4 @@ package drivers
 
 // Version returns a user-readable string showing the version of the drivers package for support purposes.
 // Update this value before release of new version of software.
-const Version = "0.13.0"
+const Version = "0.14.0"

vl53l1x/vl53l1x.go

@@ -10,8 +10,9 @@
 package vl53l1x // import "tinygo.org/x/drivers/vl53l1x"
 
 import (
-	"machine"
 	"time"
+
+	"tinygo.org/x/drivers"
 )
 
 type DistanceMode uint8
@@ -35,7 +36,7 @@ type resultBuffer struct {
 
 // Device wraps an I2C connection to a VL53L1X device.
 type Device struct {
-	bus                machine.I2C
+	bus                drivers.I2C
 	Address            uint16
 	mode               DistanceMode
 	timeout            uint32
@@ -52,7 +53,7 @@ type Device struct {
 // configured.
 //
 // This function only creates the Device object, it does not touch the device.
-func New(bus machine.I2C) Device {
+func New(bus drivers.I2C) Device {
 	return Device{
 		bus:     bus,
 		Address: Address,

waveshare-epd/epd4in2/epd4in2.go

@@ -0,0 +1,355 @@
+// Package epd4in2 implements a driver for Waveshare 4.2in black and white e-paper device.
+//
+// Derived from:
+//   https://github.com/tinygo-org/drivers/tree/master/waveshare-epd
+//   https://github.com/waveshare/e-Paper/blob/master/Arduino/epd4in2/epd4in2.cpp
+//
+// Datasheet: https://www.waveshare.com/wiki/4.2inch_e-Paper_Module
+//
+package epd4in2
+
+import (
+	"image/color"
+	"machine"
+	"time"
+)
+
+type Config struct {
+	Width        int16 // Width is the display resolution
+	Height       int16
+	LogicalWidth int16    // LogicalWidth must be a multiple of 8 and same size or bigger than Width
+	Rotation     Rotation // Rotation is clock-wise
+}
+
+type Device struct {
+	bus          machine.SPI
+	cs           machine.Pin
+	dc           machine.Pin
+	rst          machine.Pin
+	busy         machine.Pin
+	logicalWidth int16
+	width        int16
+	height       int16
+	buffer       []uint8
+	bufferLength uint32
+	rotation     Rotation
+}
+
+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 {
+	csPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	dcPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	rstPin.Configure(machine.PinConfig{Mode: machine.PinOutput})
+	busyPin.Configure(machine.PinConfig{Mode: machine.PinInput})
+	return Device{
+		bus:  bus,
+		cs:   csPin,
+		dc:   dcPin,
+		rst:  rstPin,
+		busy: busyPin,
+	}
+}
+
+// Configure sets up the device.
+func (d *Device) Configure(cfg Config) {
+	if cfg.LogicalWidth != 0 {
+		d.logicalWidth = cfg.LogicalWidth
+	} else {
+		d.logicalWidth = EPD_WIDTH
+	}
+	if cfg.Width != 0 {
+		d.width = cfg.Width
+	} else {
+		d.width = EPD_WIDTH
+	}
+	if cfg.Height != 0 {
+		d.height = cfg.Height
+	} else {
+		d.height = EPD_HEIGHT
+	}
+	d.rotation = cfg.Rotation
+	d.bufferLength = (uint32(d.logicalWidth) * uint32(d.height)) / 8
+	d.buffer = make([]uint8, d.bufferLength)
+	for i := uint32(0); i < d.bufferLength; i++ {
+		d.buffer[i] = 0xFF
+	}
+
+	d.cs.Low()
+	d.dc.Low()
+	d.rst.Low()
+
+	d.Reset()
+	d.SendCommand(POWER_SETTING)
+	d.SendData(0x03) // VDS_EN, VDG_EN
+	d.SendData(0x00) // VCOM_HV, VGHL_LV[1], VGHL_LV[0]
+	d.SendData(0x2b) // VDH
+	d.SendData(0x2b) // VDL
+	d.SendData(0xff) // VDHR
+	d.SendCommand(BOOSTER_SOFT_START)
+	d.SendData(0x17)
+	d.SendData(0x17)
+	d.SendData(0x17) //07 0f 17 1f 27 2F 37 2f
+	d.SendCommand(POWER_ON)
+	d.WaitUntilIdle()
+	d.SendCommand(PANEL_SETTING)
+	d.SendData(0xbf) // KW-BF   KWR-AF  BWROTP 0f
+	d.SendData(0x0b)
+	d.SendCommand(PLL_CONTROL)
+	d.SendData(0x3c) // 3A 100HZ   29 150Hz 39 200HZ  31 171HZ
+}
+
+// Reset resets the device
+func (d *Device) Reset() {
+	d.rst.Low()
+	time.Sleep(200 * time.Millisecond)
+	d.rst.High()
+	time.Sleep(200 * time.Millisecond)
+}
+
+// DeepSleep puts the display into deepsleep
+func (d *Device) DeepSleep() {
+	d.SendCommand(VCOM_AND_DATA_INTERVAL_SETTING)
+	d.SendData(0x17)              //border floating
+	d.SendCommand(VCM_DC_SETTING) //VCOM to 0V
+	d.SendCommand(PANEL_SETTING)
+	time.Sleep(100 * time.Millisecond)
+
+	d.SendCommand(POWER_SETTING) //VG&VS to 0V fast
+	d.SendData(0x00)
+	d.SendData(0x00)
+	d.SendData(0x00)
+	d.SendData(0x00)
+	d.SendData(0x00)
+	time.Sleep(100 * time.Millisecond)
+
+	d.SendCommand(POWER_OFF) //power off
+	d.WaitUntilIdle()
+	d.SendCommand(DEEP_SLEEP) //deep sleep
+	d.SendData(0xA5)
+}
+
+// SendCommand sends a command to the display
+func (d *Device) SendCommand(command uint8) {
+	d.sendDataCommand(true, command)
+}
+
+// SendData sends a data byte to the display
+func (d *Device) SendData(data uint8) {
+	d.sendDataCommand(false, data)
+}
+
+// sendDataCommand sends image data or a command to the screen
+func (d *Device) sendDataCommand(isCommand bool, data uint8) {
+	if isCommand {
+		d.dc.Low()
+	} else {
+		d.dc.High()
+	}
+	d.cs.Low()
+	d.bus.Transfer(data)
+	d.cs.High()
+}
+
+// SetLUT sets the look up tables for full or partial updates
+func (d *Device) SetLUT() {
+	lut_vcom0 := []uint8{
+		0x00, 0x17, 0x00, 0x00, 0x00, 0x02,
+		0x00, 0x17, 0x17, 0x00, 0x00, 0x02,
+		0x00, 0x0A, 0x01, 0x00, 0x00, 0x01,
+		0x00, 0x0E, 0x0E, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, // 44 bytes, unlike the others
+	}
+	lut_ww := []uint8{
+		0x40, 0x17, 0x00, 0x00, 0x00, 0x02,
+		0x90, 0x17, 0x17, 0x00, 0x00, 0x02,
+		0x40, 0x0A, 0x01, 0x00, 0x00, 0x01,
+		0xA0, 0x0E, 0x0E, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}
+	lut_bw := []uint8{
+		0x40, 0x17, 0x00, 0x00, 0x00, 0x02,
+		0x90, 0x17, 0x17, 0x00, 0x00, 0x02,
+		0x40, 0x0A, 0x01, 0x00, 0x00, 0x01,
+		0xA0, 0x0E, 0x0E, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}
+	lut_bb := []uint8{
+		0x80, 0x17, 0x00, 0x00, 0x00, 0x02,
+		0x90, 0x17, 0x17, 0x00, 0x00, 0x02,
+		0x80, 0x0A, 0x01, 0x00, 0x00, 0x01,
+		0x50, 0x0E, 0x0E, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}
+	lut_wb := []uint8{
+		0x80, 0x17, 0x00, 0x00, 0x00, 0x02,
+		0x90, 0x17, 0x17, 0x00, 0x00, 0x02,
+		0x80, 0x0A, 0x01, 0x00, 0x00, 0x01,
+		0x50, 0x0E, 0x0E, 0x00, 0x00, 0x02,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	}
+
+	d.SendCommand(LUT_FOR_VCOM) //vcom
+	for count := 0; count < 44; count++ {
+		d.SendData(lut_vcom0[count])
+	}
+
+	d.SendCommand(LUT_WHITE_TO_WHITE) //ww --
+	for count := 0; count < 42; count++ {
+		d.SendData(lut_ww[count])
+	}
+
+	d.SendCommand(LUT_BLACK_TO_WHITE) //bw r
+	for count := 0; count < 42; count++ {
+		d.SendData(lut_bw[count])
+	}
+
+	d.SendCommand(LUT_WHITE_TO_BLACK) //wb w
+	for count := 0; count < 42; count++ {
+		d.SendData(lut_bb[count])
+	}
+
+	d.SendCommand(LUT_BLACK_TO_BLACK) //bb b
+	for count := 0; count < 42; count++ {
+		d.SendData(lut_wb[count])
+	}
+}
+
+// SetPixel modifies the internal buffer in a single pixel.
+// The display have 2 colors: black and white
+// We use RGBA(0,0,0, 255) as white (transparent)
+// Anything else as black
+func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
+	x, y = d.xy(x, y)
+	if x < 0 || x >= d.logicalWidth || y < 0 || y >= d.height {
+		return
+	}
+	byteIndex := (uint32(x) + uint32(y)*uint32(d.logicalWidth)) / 8
+	if c.R == 0 && c.G == 0 && c.B == 0 { // TRANSPARENT / WHITE
+		d.buffer[byteIndex] |= 0x80 >> uint8(x%8)
+	} else { // WHITE / EMPTY
+		d.buffer[byteIndex] &^= 0x80 >> uint8(x%8)
+	}
+}
+
+// Display sends the buffer to the screen.
+func (d *Device) Display() error {
+	d.SendCommand(RESOLUTION_SETTING)
+	d.SendData(uint8(d.height >> 8))
+	d.SendData(uint8(d.logicalWidth & 0xff))
+	d.SendData(uint8(d.height >> 8))
+	d.SendData(uint8(d.height & 0xff))
+
+	d.SendCommand(VCM_DC_SETTING)
+	d.SendData(0x12)
+
+	d.SendCommand(VCOM_AND_DATA_INTERVAL_SETTING)
+	d.SendCommand(0x97) //VBDF 17|D7 VBDW 97  VBDB 57  VBDF F7  VBDW 77  VBDB 37  VBDR B7
+
+	d.SendCommand(DATA_START_TRANSMISSION_1)
+	var i int16
+	for i = 0; i < d.logicalWidth/8*d.height; i++ {
+		d.SendData(0xFF) // bit set: white, bit reset: black
+	}
+	time.Sleep(2 * time.Millisecond)
+	d.SendCommand(DATA_START_TRANSMISSION_2)
+	for i = 0; i < d.logicalWidth/8*d.height; i++ {
+		d.SendData(d.buffer[i])
+	}
+	time.Sleep(2 * time.Millisecond)
+
+	d.SetLUT()
+
+	d.SendCommand(DISPLAY_REFRESH)
+	time.Sleep(100 * time.Millisecond)
+	d.WaitUntilIdle()
+
+	return nil
+}
+
+// ClearDisplay erases the device SRAM
+func (d *Device) ClearDisplay() {
+	d.SendCommand(RESOLUTION_SETTING)
+	d.SendData(uint8(d.height >> 8))
+	d.SendData(uint8(d.logicalWidth & 0xff))
+	d.SendData(uint8(d.height >> 8))
+	d.SendData(uint8(d.height & 0xff))
+
+	d.SendCommand(DATA_START_TRANSMISSION_1)
+	time.Sleep(2 * time.Millisecond)
+	var i int16
+	for i = 0; i < d.logicalWidth/8*d.height; i++ {
+		d.SendData(0xFF)
+	}
+	time.Sleep(2 * time.Millisecond)
+	d.SendCommand(DATA_START_TRANSMISSION_2)
+	time.Sleep(2 * time.Millisecond)
+	for i = 0; i < d.logicalWidth/8*d.height; i++ {
+		d.SendData(0xFF)
+	}
+	time.Sleep(2 * time.Millisecond)
+
+	d.SetLUT()
+	d.SendCommand(DISPLAY_REFRESH)
+	time.Sleep(100 * time.Millisecond)
+	d.WaitUntilIdle()
+}
+
+// WaitUntilIdle waits until the display is ready
+func (d *Device) WaitUntilIdle() {
+	for d.busy.Get() {
+		time.Sleep(100 * time.Millisecond)
+	}
+}
+
+// IsBusy returns the busy status of the display
+func (d *Device) IsBusy() bool {
+	return d.busy.Get()
+}
+
+// ClearBuffer sets the buffer to 0xFF (white)
+func (d *Device) ClearBuffer() {
+	for i := uint32(0); i < d.bufferLength; i++ {
+		d.buffer[i] = 0xFF
+	}
+}
+
+// Size returns the current size of the display.
+func (d *Device) Size() (w, h int16) {
+	if d.rotation == ROTATION_90 || d.rotation == ROTATION_270 {
+		return d.height, d.logicalWidth
+	}
+	return d.logicalWidth, d.height
+}
+
+// SetRotation changes the rotation (clock-wise) of the device
+func (d *Device) SetRotation(rotation Rotation) {
+	d.rotation = rotation
+}
+
+// xy chages the coordinates according to the rotation
+func (d *Device) xy(x, y int16) (int16, int16) {
+	switch d.rotation {
+	case NO_ROTATION:
+		return x, y
+	case ROTATION_90:
+		return d.width - y - 1, x
+	case ROTATION_180:
+		return d.width - x - 1, d.height - y - 1
+	case ROTATION_270:
+		return y, d.height - x - 1
+	}
+	return x, y
+}

waveshare-epd/epd4in2/registers.go

@@ -0,0 +1,55 @@
+package epd4in2
+
+// Derived from https://github.com/waveshare/e-Paper/blob/master/Arduino/epd4in2/epd4in2.h
+
+// Registers
+const (
+	// Display resolution
+	EPD_WIDTH  = 400
+	EPD_HEIGHT = 300
+
+	// EPD4IN2 commands
+	PANEL_SETTING                  = 0x00
+	POWER_SETTING                  = 0x01
+	POWER_OFF                      = 0x02
+	POWER_OFF_SEQUENCE_SETTING     = 0x03
+	POWER_ON                       = 0x04
+	POWER_ON_MEASURE               = 0x05
+	BOOSTER_SOFT_START             = 0x06
+	DEEP_SLEEP                     = 0x07
+	DATA_START_TRANSMISSION_1      = 0x10
+	DATA_STOP                      = 0x11
+	DISPLAY_REFRESH                = 0x12
+	DATA_START_TRANSMISSION_2      = 0x13
+	LUT_FOR_VCOM                   = 0x20
+	LUT_WHITE_TO_WHITE             = 0x21
+	LUT_BLACK_TO_WHITE             = 0x22
+	LUT_WHITE_TO_BLACK             = 0x23
+	LUT_BLACK_TO_BLACK             = 0x24
+	PLL_CONTROL                    = 0x30
+	TEMPERATURE_SENSOR_COMMAND     = 0x40
+	TEMPERATURE_SENSOR_SELECTION   = 0x41
+	TEMPERATURE_SENSOR_WRITE       = 0x42
+	TEMPERATURE_SENSOR_READ        = 0x43
+	VCOM_AND_DATA_INTERVAL_SETTING = 0x50
+	LOW_POWER_DETECTION            = 0x51
+	TCON_SETTING                   = 0x60
+	RESOLUTION_SETTING             = 0x61
+	GSST_SETTING                   = 0x65
+	GET_STATUS                     = 0x71
+	AUTO_MEASUREMENT_VCOM          = 0x80
+	READ_VCOM_VALUE                = 0x81
+	VCM_DC_SETTING                 = 0x82
+	PARTIAL_WINDOW                 = 0x90
+	PARTIAL_IN                     = 0x91
+	PARTIAL_OUT                    = 0x92
+	PROGRAM_MODE                   = 0xA0
+	ACTIVE_PROGRAMMING             = 0xA1
+	READ_OTP                       = 0xA2
+	POWER_SAVING                   = 0xE3
+
+	NO_ROTATION  Rotation = 0
+	ROTATION_90  Rotation = 1 // 90 degrees clock-wise rotation
+	ROTATION_180 Rotation = 2
+	ROTATION_270 Rotation = 3
+)

ws2812/ws2812_xtensa.go

@@ -0,0 +1,346 @@
+// +build xtensa
+
+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()
+
+	switch machine.CPUFrequency() {
+	case 160e6: // 160MHz
+		// See:
+		// https://wp.josh.com/2014/05/13/ws2812-neopixels-are-not-so-finicky-once-you-get-to-know-them/
+		// Because I do not know the exact instruction timings, I'm going to
+		// assume that every instruction executes in one cycle. Branches and
+		// load/stores will probably be slower than that, but as long as all
+		// timings are only increased a little bit this should not be a problem
+		// (see above post).
+		// T0H: 40  cycles or  333.3ns
+		// T0L: 131 cycles or 1091.7ns
+		//   +: 171 cycles or 1425.0ns
+		// T1H: 95  cycles or  791.7ns
+		// T1L: 75  cycles or  625.0ns
+		//   +: 170 cycles or 1416.7ns
+		// Some documentation:
+		// http://cholla.mmto.org/esp8266/xtensa.html
+		// https://0x04.net/~mwk/doc/xtensa.pdf
+		device.AsmFull(`
+		1: // send_bit
+			s32i  {maskSet}, {portSet}, 0     // [1]  T0H and T1H start here
+			nop                               // [37]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			slli  {value}, {value}, 1         // [1]  shift {value} to the left by 1
+			bbsi  {value}, 8, 2f              // [1]  branch to skip_store if bit 8 is set
+			s32i  {maskClear}, {portClear}, 0 // [1]  T0H -> T0L transition
+		2: // skip_store
+			nop                               // [55]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			s32i  {maskClear}, {portClear}, 0 // [1]  T1H -> T1L transition
+			nop                               // [72]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			addi  {i}, {i}, -1                // [1]
+			bnez {i}, 1b                      // [1]  send_bit, T1H and T1L end here
+
+			// Restore original values after modifying them in the inline
+			// assembly. Not doing that would result in undefined behavior as
+			// the compiler doesn't know we're modifying these values.
+			movi.n {i}, 8
+			slli  {value}, {value}, 8
+		`, map[string]interface{}{
+			// Note: casting pointers to uintptr here because of what might be
+			// an Xtensa backend bug with inline assembly.
+			"value":     uint32(c),
+			"i":         8,
+			"maskSet":   maskSet,
+			"portSet":   uintptr(unsafe.Pointer(portSet)),
+			"maskClear": maskClear,
+			"portClear": uintptr(unsafe.Pointer(portClear)),
+		})
+		return nil
+	case 80e6: // 80MHz
+		// See docs for 160MHz.
+		// T0H: 21 cycles or  262.5ns
+		// T0L: 67 cycles or  837.5ns
+		//   +: 88 cycles or 1100.0ns
+		// T1H: 47 cycles or  587.5ns
+		// T1L: 39 cycles or  487.5ns
+		//   +: 86 cycles or 1075.0ns
+		device.AsmFull(`
+		1: // send_bit
+			s32i  {maskSet}, {portSet}, 0     // [1]  T0H and T1H start here
+			nop                               // [18]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			slli  {value}, {value}, 1         // [1]  shift {value} to the left by 1
+			bbsi  {value}, 8, 2f              // [1]  branch to skip_store if bit 8 is set
+			s32i  {maskClear}, {portClear}, 0 // [1]  T0H -> T0L transition
+		2: // skip_store
+			nop                               // [27]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			s32i  {maskClear}, {portClear}, 0 // [1]  T1H -> T1L transition
+			nop                               // [36]
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			nop
+			addi  {i}, {i}, -1                // [1]
+			bnez {i}, 1b                      // [1]  send_bit, T1H and T1L end here
+
+			// Restore original values after modifying them in the inline
+			// assembly. Not doing that would result in undefined behavior as
+			// the compiler doesn't know we're modifying these values.
+			movi.n {i}, 8
+			slli  {value}, {value}, 8
+		`, map[string]interface{}{
+			// Note: casting pointers to uintptr here because of what might be
+			// an Xtensa backend bug with inline assembly.
+			"value":     uint32(c),
+			"i":         8,
+			"maskSet":   maskSet,
+			"portSet":   uintptr(unsafe.Pointer(portSet)),
+			"maskClear": maskClear,
+			"portClear": uintptr(unsafe.Pointer(portClear)),
+		})
+		return nil
+	default:
+		return errUnknownClockSpeed
+	}
+}