Add Waveshare 4.2in B/W e-paper driver

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

README.md

@@ -52,7 +52,7 @@ func main() {
 
 ## Currently supported devices
 
-The following 52 devices are supported.
+The following 53 devices are supported.
 
 | Device Name | Interface Type |
 |----------|-------------|
@@ -107,6 +107,7 @@ The following 52 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

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)
+		}
+	}
+}