waveshare(ssd1680): Add driver for waveshare 2.9 inch v2 epaper

- Waveshare 2.9in v2 epaper uses a different IC (SSD1680) than the v1. This commit
takes the code from v1 and modifies them for v2.
- Datasheets:
    - https://files.waveshare.com/upload/7/79/2.9inch-e-paper-v2-specification.pdf
    - https://cdn-learn.adafruit.com/assets/assets/000/097/631/original/SSD1680_Datasheet.pdf?1607625960
- Code reference: https://github.com/waveshareteam/e-Paper/raw/refs/heads/master/RaspberryPi_JetsonNano/c/lib/e-Paper/EPD_2in9_V2.c
- Fixes #627

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>
Assisted-by: Claude Code

examples/waveshare-epd/epd2in9v2/main.go

@@ -0,0 +1,137 @@
+package main
+
+import (
+	"image/color"
+	"machine"
+	"time"
+
+	"tinygo.org/x/drivers/waveshare-epd/epd2in9v2"
+)
+
+var display epd2in9v2.Device
+
+func main() {
+	machine.SPI0.Configure(machine.SPIConfig{
+		Frequency: 12000000,
+		SCK:       machine.EPD_SCK_PIN,
+		SDO:       machine.EPD_SDO_PIN,
+	})
+
+	display = epd2in9v2.New(
+		machine.SPI0,
+		machine.EPD_CS_PIN,
+		machine.EPD_DC_PIN,
+		machine.EPD_RESET_PIN,
+		machine.EPD_BUSY_PIN,
+	)
+	display.Configure(epd2in9v2.Config{
+		Rotation: epd2in9v2.ROTATION_270,
+		Speed:    epd2in9v2.SPEED_DEFAULT,
+		Blocking: true,
+	})
+
+	black := color.RGBA{0, 0, 0, 255}
+	white := color.RGBA{255, 255, 255, 255}
+
+	// --- Step 1: clear to white ---
+	println("epd2in9v2: clearing display")
+	display.ClearBuffer()
+	display.Display()
+	time.Sleep(2 * time.Second)
+
+	// --- Step 2: full refresh checkerboard ---
+	println("epd2in9v2: drawing checkerboard (full refresh)")
+	w, h := display.Size()
+	for i := int16(0); i < w/8; i++ {
+		for j := int16(0); j < h/8; j++ {
+			if (i+j)%2 == 0 {
+				fillRect(i*8, j*8, 8, 8, black)
+			}
+		}
+	}
+	display.Display()
+	time.Sleep(2 * time.Second)
+
+	// --- Step 3: fast refresh - draw border and diagonal cross ---
+	println("epd2in9v2: switching to fast refresh")
+	display.SetSpeed(epd2in9v2.SPEED_FAST)
+	display.ClearBuffer()
+
+	for x := int16(0); x < w; x++ {
+		display.SetPixel(x, 0, black)
+		display.SetPixel(x, h-1, black)
+	}
+	for y := int16(0); y < h; y++ {
+		display.SetPixel(0, y, black)
+		display.SetPixel(w-1, y, black)
+	}
+	for i := int16(0); i < w && i < h; i++ {
+		display.SetPixel(i, i*h/w, black)
+		display.SetPixel(w-1-i, i*h/w, black)
+	}
+
+	display.Display()
+	time.Sleep(2 * time.Second)
+
+	// --- Step 4: partial refresh counter ---
+	println("epd2in9v2: partial refresh demo")
+	display.SetSpeed(epd2in9v2.SPEED_DEFAULT)
+	display.ClearBuffer()
+
+	println("epd2in9v2: setting base image")
+	display.DisplayWithBase()
+
+	for count := 0; count < 10; count++ {
+		cx := int16(120)
+		cy := int16(50)
+		fillRect(cx, cy, 60, 20, white)
+
+		digit := int16(count % 10)
+		drawDigit(cx+22, cy+2, digit, black)
+
+		display.DisplayPartial()
+		time.Sleep(500 * time.Millisecond)
+	}
+	time.Sleep(2 * time.Second)
+
+	// --- Step 5: sleep ---
+	println("epd2in9v2: entering deep sleep")
+	display.ClearBuffer()
+	display.Display()
+	display.Sleep()
+	println("epd2in9v2: done, you can remove power")
+}
+
+func fillRect(x, y, w, h int16, c color.RGBA) {
+	for i := x; i < x+w; i++ {
+		for j := y; j < y+h; j++ {
+			display.SetPixel(i, j, c)
+		}
+	}
+}
+
+// drawDigit draws a simple 3x5-pixel-block digit (each block 4x3 px) at position (x,y).
+func drawDigit(x, y, digit int16, c color.RGBA) {
+	segments := [10][5]uint8{
+		{0x7, 0x5, 0x5, 0x5, 0x7}, // 0
+		{0x2, 0x2, 0x2, 0x2, 0x2}, // 1
+		{0x7, 0x1, 0x7, 0x4, 0x7}, // 2
+		{0x7, 0x1, 0x7, 0x1, 0x7}, // 3
+		{0x5, 0x5, 0x7, 0x1, 0x1}, // 4
+		{0x7, 0x4, 0x7, 0x1, 0x7}, // 5
+		{0x7, 0x4, 0x7, 0x5, 0x7}, // 6
+		{0x7, 0x1, 0x1, 0x1, 0x1}, // 7
+		{0x7, 0x5, 0x7, 0x5, 0x7}, // 8
+		{0x7, 0x5, 0x7, 0x1, 0x7}, // 9
+	}
+	if digit < 0 || digit > 9 {
+		return
+	}
+	for row := int16(0); row < 5; row++ {
+		for col := int16(0); col < 3; col++ {
+			if segments[digit][row]&(0x4>>uint(col)) != 0 {
+				fillRect(x+col*4, y+row*3, 4, 3, c)
+			}
+		}
+	}
+}