support for SSD1306 displays using I2C or SPI, several screen sizes (#49)

supported too

.circleci/config.yml

@@ -32,6 +32,8 @@ jobs:
       - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/mpu6050/main.go
       - run: tinygo build -size short -o test.elf -target=microbit ./examples/pcd8544/setbuffer/main.go
       - run: tinygo build -size short -o test.elf -target=microbit ./examples/pcd8544/setpixel/main.go
+      - run: tinygo build -size short -o test.elf -target=microbit ./examples/ssd1306/i2c_128x32/main.go
+      - run: tinygo build -size short -o test.elf -target=microbit ./examples/ssd1306/spi_128x64/main.go
       - run: tinygo build -size short -o test.elf -target=circuitplay-express ./examples/thermistor/main.go
       - run: tinygo build -size short -o test.elf -target=itsybitsy-m0 ./examples/vl53l1x/main.go
       - run: tinygo build -size short -o test.elf -target=circuitplay-express ./examples/ws2812/main.go

README.md

@@ -68,6 +68,7 @@ func main() {
 | [MMA8653 accelerometer](https://www.nxp.com/docs/en/data-sheet/MMA8653FC.pdf) | I2C |
 | [MPU6050 accelerometer/gyroscope](https://store.invensense.com/datasheets/invensense/MPU-6050_DataSheet_V3%204.pdf) | I2C |
 | [PCD8544 display](http://eia.udg.edu/~forest/PCD8544_1.pdf) | SPI |
+| [SSD1306 OLED display](https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf) | I2C / SPI |
 | [Thermistor](https://www.farnell.com/datasheets/33552.pdf) | ADC |
 | [VL53L1X time-of-flight distance sensor](https://www.st.com/resource/en/datasheet/vl53l1x.pdf) | I2C |
 | [WS2812 RGB LED](https://cdn-shop.adafruit.com/datasheets/WS2812.pdf) | GPIO |

examples/ssd1306/i2c_128x32/main.go

@@ -0,0 +1,51 @@
+package i2c_128x32
+
+import (
+	"machine"
+
+	"image/color"
+	"time"
+
+	"github.com/tinygo-org/drivers/ssd1306"
+)
+
+func main() {
+	machine.I2C0.Configure(machine.I2CConfig{
+		Frequency: machine.TWI_FREQ_400KHZ,
+	})
+
+	display := ssd1306.NewI2C(machine.I2C0)
+	display.Configure(ssd1306.Config{
+		Address: ssd1306.Address_128_32,
+		Width:   128,
+		Height:  32,
+	})
+
+	display.ClearDisplay()
+
+	x := int16(0)
+	y := int16(0)
+	deltaX := int16(1)
+	deltaY := int16(1)
+	for {
+		pixel := display.GetPixel(x, y)
+		c := color.RGBA{255, 255, 255, 255}
+		if pixel {
+			c = color.RGBA{0, 0, 0, 255}
+		}
+		display.SetPixel(x, y, c)
+		display.Display()
+
+		x += deltaX
+		y += deltaY
+
+		if x == 0 || x == 127 {
+			deltaX = -deltaX
+		}
+
+		if y == 0 || y == 31 {
+			deltaY = -deltaY
+		}
+		time.Sleep(1 * time.Millisecond)
+	}
+}

examples/ssd1306/spi_128x64/main.go

@@ -0,0 +1,48 @@
+package i2c_128x64
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"github.com/tinygo-org/drivers/ssd1306"
+)
+
+func main() {
+	machine.SPI0.Configure(machine.SPIConfig{
+		Frequency: 8000000,
+	})
+	display := ssd1306.NewSPI(machine.SPI0, machine.P8, machine.P7, machine.P9)
+	display.Configure(ssd1306.Config{
+		Width:  128,
+		Height: 64,
+	})
+
+	display.ClearDisplay()
+
+	x := int16(64)
+	y := int16(32)
+	deltaX := int16(1)
+	deltaY := int16(1)
+	for {
+		pixel := display.GetPixel(x, y)
+		c := color.RGBA{255, 255, 255, 255}
+		if pixel {
+			c = color.RGBA{0, 0, 0, 255}
+		}
+		display.SetPixel(x, y, c)
+		display.Display()
+
+		x += deltaX
+		y += deltaY
+
+		if x == 0 || x == 127 {
+			deltaX = -deltaX
+		}
+
+		if y == 0 || y == 63 {
+			deltaY = -deltaY
+		}
+		time.Sleep(1 * time.Millisecond)
+	}
+}

ssd1306/registers.go

@@ -0,0 +1,41 @@
+package ssd1306
+
+// Registers
+const (
+	Address        = 0x3D
+	Address_128_32 = 0x3C
+
+	SETCONTRAST                          = 0x81
+	DISPLAYALLON_RESUME                  = 0xA4
+	DISPLAYALLON                         = 0xA5
+	NORMALDISPLAY                        = 0xA6
+	INVERTDISPLAY                        = 0xA7
+	DISPLAYOFF                           = 0xAE
+	DISPLAYON                            = 0xAF
+	SETDISPLAYOFFSET                     = 0xD3
+	SETCOMPINS                           = 0xDA
+	SETVCOMDETECT                        = 0xDB
+	SETDISPLAYCLOCKDIV                   = 0xD5
+	SETPRECHARGE                         = 0xD9
+	SETMULTIPLEX                         = 0xA8
+	SETLOWCOLUMN                         = 0x00
+	SETHIGHCOLUMN                        = 0x10
+	SETSTARTLINE                         = 0x40
+	MEMORYMODE                           = 0x20
+	COLUMNADDR                           = 0x21
+	PAGEADDR                             = 0x22
+	COMSCANINC                           = 0xC0
+	COMSCANDEC                           = 0xC8
+	SEGREMAP                             = 0xA0
+	CHARGEPUMP                           = 0x8D
+	ACTIVATE_SCROLL                      = 0x2F
+	DEACTIVATE_SCROLL                    = 0x2E
+	SET_VERTICAL_SCROLL_AREA             = 0xA3
+	RIGHT_HORIZONTAL_SCROLL              = 0x26
+	LEFT_HORIZONTAL_SCROLL               = 0x27
+	VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL = 0x29
+	VERTICAL_AND_LEFT_HORIZONTAL_SCROLL  = 0x2A
+
+	EXTERNALVCC  VccMode = 0x1
+	SWITCHCAPVCC VccMode = 0x2
+)

ssd1306/ssd1306.go

@@ -0,0 +1,302 @@
+// Package ssd1306 implements a driver for the SSD1306 led matrix controller, it comes in various colors and screen sizes.
+//
+// Datasheet: https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf
+package ssd1306
+
+import (
+	"errors"
+	"image/color"
+	"machine"
+	"time"
+)
+
+// Device wraps an SPI connection.
+type Device struct {
+	bus        Buser
+	buffer     []byte
+	width      int16
+	height     int16
+	bufferSize int16
+	vccState   VccMode
+}
+
+// Config is the configuration for the display
+type Config struct {
+	Width    int16
+	Height   int16
+	VccState VccMode
+	Address  uint16
+}
+
+type I2CBus struct {
+	wire    machine.I2C
+	Address uint16
+}
+
+type SPIBus struct {
+	wire     machine.SPI
+	dcPin    machine.GPIO
+	resetPin machine.GPIO
+	csPin    machine.GPIO
+}
+
+type Buser interface {
+	configure()
+	tx(data []byte, isCommand bool)
+	setAddress(address uint16)
+}
+
+type VccMode uint8
+
+// NewI2C creates a new SSD1306 connection. The I2C wire must already be configured.
+func NewI2C(bus machine.I2C) Device {
+	return Device{
+		bus: &I2CBus{
+			wire:    bus,
+			Address: Address,
+		},
+	}
+}
+
+// NewSPI creates a new SSD1306 connection. The SPI wire must already be configured.
+func NewSPI(bus machine.SPI, dcPin uint8, resetPin uint8, csPin uint8) Device {
+	pinDc := machine.GPIO{dcPin}
+	pinDc.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	pinReset := machine.GPIO{resetPin}
+	pinReset.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	pinCs := machine.GPIO{csPin}
+	pinCs.Configure(machine.GPIOConfig{Mode: machine.GPIO_OUTPUT})
+	return Device{
+		bus: &SPIBus{
+			wire:     bus,
+			dcPin:    pinDc,
+			resetPin: pinReset,
+			csPin:    pinCs,
+		},
+	}
+}
+
+// Configure initializes the display with default configuration
+func (d *Device) Configure(cfg Config) {
+	if cfg.Width != 0 {
+		d.width = cfg.Width
+	} else {
+		d.width = 128
+	}
+	if cfg.Height != 0 {
+		d.height = cfg.Height
+	} else {
+		d.height = 64
+	}
+	if cfg.Address != 0 {
+		d.bus.setAddress(cfg.Address)
+	}
+	if cfg.VccState != 0 {
+		d.vccState = cfg.VccState
+	} else {
+		d.vccState = SWITCHCAPVCC
+	}
+	d.bufferSize = d.width * d.height / 8
+	d.buffer = make([]byte, d.bufferSize)
+
+	d.bus.configure()
+
+	time.Sleep(100 * time.Nanosecond)
+	d.Command(DISPLAYOFF)
+	d.Command(SETDISPLAYCLOCKDIV)
+	d.Command(0x80)
+	d.Command(SETMULTIPLEX)
+	d.Command(uint8(d.height - 1))
+	d.Command(SETDISPLAYOFFSET)
+	d.Command(0x0)
+	d.Command(SETSTARTLINE | 0x0)
+	d.Command(CHARGEPUMP)
+	if d.vccState == EXTERNALVCC {
+		d.Command(0x10)
+	} else {
+		d.Command(0x14)
+	}
+	d.Command(MEMORYMODE)
+	d.Command(0x00)
+	d.Command(SEGREMAP | 0x1)
+	d.Command(COMSCANDEC)
+
+	if (d.width == 128 && d.height == 64) || (d.width == 64 && d.height == 48) { // 128x64 or 64x48
+		d.Command(SETCOMPINS)
+		d.Command(0x12)
+		d.Command(SETCONTRAST)
+		if d.vccState == EXTERNALVCC {
+			d.Command(0x9F)
+		} else {
+			d.Command(0xCF)
+		}
+	} else if d.width == 128 && d.height == 32 { // 128x32
+		d.Command(SETCOMPINS)
+		d.Command(0x02)
+		d.Command(SETCONTRAST)
+		d.Command(0x8F)
+	} else if d.width == 96 && d.height == 16 { // 96x16
+		d.Command(SETCOMPINS)
+		d.Command(0x2)
+		d.Command(SETCONTRAST)
+		if d.vccState == EXTERNALVCC {
+			d.Command(0x10)
+		} else {
+			d.Command(0xAF)
+		}
+	} else {
+		// fail silently, it might work
+		println("there's no configuration for this display's size")
+	}
+
+	d.Command(SETPRECHARGE)
+	if d.vccState == EXTERNALVCC {
+		d.Command(0x22)
+	} else {
+		d.Command(0xF1)
+	}
+	d.Command(SETVCOMDETECT)
+	d.Command(0x40)
+	d.Command(DISPLAYALLON_RESUME)
+	d.Command(NORMALDISPLAY)
+	d.Command(DEACTIVATE_SCROLL)
+	d.Command(DISPLAYON)
+}
+
+// ClearBuffer clears the image buffer
+func (d *Device) ClearBuffer() {
+	for i := int16(0); i < d.bufferSize; i++ {
+		d.buffer[i] = 0
+	}
+}
+
+// ClearDisplay clears the image buffer and clear the display
+func (d *Device) ClearDisplay() {
+	d.ClearBuffer()
+	d.Display()
+}
+
+// Display sends the whole buffer to the screen
+func (d *Device) Display() error {
+	// In the 128x64 (SPI) screen resetting to 0x0 after 128 times corrupt the buffer
+	// Since we're printing the whole buffer, avoid resetting it
+	if d.width != 128 || d.height != 64 {
+		d.Command(COLUMNADDR)
+		d.Command(0)
+		d.Command(uint8(d.width - 1))
+		d.Command(PAGEADDR)
+		d.Command(0)
+		d.Command(uint8(d.height/8) - 1)
+	}
+
+	d.Tx(d.buffer, false)
+	return nil
+}
+
+// SetPixel enables or disables a pixel in the buffer
+// color.RGBA{0, 0, 0, 255} is consider transparent, anything else
+// with enable a pixel on the screen
+func (d *Device) SetPixel(x int16, y int16, c color.RGBA) {
+	if x < 0 || x >= d.width || y < 0 || y >= d.height {
+		return
+	}
+	byteIndex := x + (y/8)*d.width
+	if c.R != 0 || c.G != 0 || c.B != 0 {
+		d.buffer[byteIndex] |= 1 << uint8(y%8)
+	} else {
+		d.buffer[byteIndex] &^= 1 << uint8(y%8)
+	}
+}
+
+// GetPixel returns if the specified pixel is on (true) or off (false)
+func (d *Device) GetPixel(x int16, y int16) bool {
+	if x < 0 || x >= d.width || y < 0 || y >= d.height {
+		return false
+	}
+	byteIndex := x + (y/8)*d.width
+	return (d.buffer[byteIndex] >> uint8(y%8) & 0x1) == 1
+}
+
+// SetBuffer changes the whole buffer at once
+func (d *Device) SetBuffer(buffer []byte) error {
+	if int16(len(buffer)) != d.bufferSize {
+		//return ErrBuffer
+		return errors.New("Wrong size buffer")
+	}
+	for i := int16(0); i < d.bufferSize; i++ {
+		d.buffer[i] = buffer[i]
+	}
+	return nil
+}
+
+// Command sends a command to the display
+func (d *Device) Command(command uint8) {
+	d.bus.tx([]byte{command}, true)
+}
+
+// setAddress sets the address to the I2C bus
+func (b *I2CBus) setAddress(address uint16) {
+	b.Address = address
+}
+
+// setAddress does nothing, but it's required to avoid reflection
+func (b *SPIBus) setAddress(address uint16) {
+	// do nothing
+	println("trying to Configure an address on a SPI device")
+}
+
+// configure does nothing, but it's required to avoid reflection
+func (b *I2CBus) configure() {}
+
+// configure configures some pins with the SPI bus
+func (b *SPIBus) configure() {
+	b.csPin.Low()
+	b.dcPin.Low()
+	b.resetPin.Low()
+
+	b.resetPin.High()
+	time.Sleep(1 * time.Millisecond)
+	b.resetPin.Low()
+	time.Sleep(10 * time.Millisecond)
+	b.resetPin.High()
+}
+
+// Tx sends data to the display
+func (d *Device) Tx(data []byte, isCommand bool) {
+	d.bus.tx(data, isCommand)
+}
+
+// tx sends data to the display (I2CBus implementation)
+func (b *I2CBus) tx(data []byte, isCommand bool) {
+	if isCommand {
+		b.wire.WriteRegister(uint8(b.Address), 0x00, data)
+	} else {
+		b.wire.WriteRegister(uint8(b.Address), 0x40, data)
+	}
+}
+
+// tx sends data to the display (SPIBus implementation)
+func (b *SPIBus) tx(data []byte, isCommand bool) {
+	if isCommand {
+		b.csPin.High()
+		time.Sleep(1 * time.Millisecond)
+		b.dcPin.Low()
+		b.csPin.Low()
+
+		b.wire.Tx(data, nil)
+		b.csPin.High()
+	} else {
+		b.csPin.High()
+		time.Sleep(1 * time.Millisecond)
+		b.dcPin.High()
+		b.csPin.Low()
+
+		b.wire.Tx(data, nil)
+		b.csPin.High()
+	}
+}
+
+// Size returns the current size of the display.
+func (d *Device) Size() (w, h int16) {
+	return d.width, d.height
+}