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

supported too

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)
+	}
+}