rpio: basic impl of Pins and SPI interfaces for Raspberry Pi

2026-08-19 06:03:57 +00:00 · 2025-12-21 23:41:51 +01:00
parent 2a42fa7cbb
commit b990fc887f
5 changed files with 164 additions and 0 deletions
@@ -0,0 +1,91 @@
+package main
+
+// Example program for the ST7735 display (Waveshare 1.44" LCD HAT) using the rpio driver on a Raspberry Pi.
+// Build command:
+//   GOOS=linux GOARCH=arm64 go build -o rpio-example ./examples/rpio/
+
+import (
+	"fmt"
+	"image/color"
+	"time"
+
+	go_rpio "github.com/stianeikeland/go-rpio/v4"
+	"tinygo.org/x/drivers"
+	"tinygo.org/x/drivers/rpio"
+	"tinygo.org/x/drivers/st7735"
+)
+
+var (
+	black  = color.RGBA{0, 0, 0, 255}
+	colors = [...]color.RGBA{
+		{255, 0, 0, 255},   // red
+		{0, 255, 0, 255},   // green
+		{0, 0, 255, 255},   // blue
+		{255, 255, 0, 255}, // yellow
+	}
+)
+
+func main() {
+	if err := go_rpio.Open(); err != nil {
+		fmt.Println("Error opening GPIO:", err)
+		return
+	}
+	defer go_rpio.Close()
+
+	// Initialize SPI and pins
+	spi := rpio.NewSPI()
+	resetPin := rpio.NewPin(27)
+	dcPin := rpio.NewPin(25)
+	csPin := rpio.NewPin(8)
+	blPin := rpio.NewPin(24)
+
+	rotatePin := rpio.NewPin(20) // middle button on the HAT
+	rotatePin.Pin.PullUp()       // enable pull-up resistor, our wrapper sets only input mode automatically
+
+	// Initialize display
+	device := st7735.New(spi, resetPin, dcPin, csPin, blPin)
+	device.Configure(st7735.Config{
+		Width:        128,
+		Height:       128,
+		Model:        st7735.GREENTAB,
+		RowOffset:    3,
+		ColumnOffset: 2,
+	})
+	device.InvertColors(false)
+	device.EnableBacklight(true)
+	device.IsBGR(true) // no effect w/o rotation!
+	device.SetRotation(st7735.NO_ROTATION)
+
+	width, height := device.Size()
+
+	// Clear display
+	device.FillScreen(black)
+
+	// Draw rectangles in a loop, clockwise rotation of colors
+	pos := 0
+	for {
+		device.FillRectangle(0, 0, width/2, height/2, colors[(pos+0)%len(colors)])              // top left
+		device.FillRectangle(0, height/2, width/2, height/2, colors[(pos+1)%len(colors)])       // bottom left
+		device.FillRectangle(width/2, height/2, width/2, height/2, colors[(pos+2)%len(colors)]) // bottom right
+		device.FillRectangle(width/2, 0, width/2, height/2, colors[(pos+3)%len(colors)])        // top right
+		device.FillRectangle(0, 0, 10, 10, black)                                               // rotation marker
+		pos++
+
+		timeout := time.Now().Add(1 * time.Second)
+		for time.Now().Before(timeout) {
+			// check button pressed
+			if !rotatePin.Get() {
+				currentRotation := device.Rotation()
+				newRotation := (currentRotation + 1) % 4
+				device.SetRotation(drivers.Rotation(newRotation))
+				// wait for button release
+				for !rotatePin.Get() {
+					time.Sleep(10 * time.Millisecond)
+				}
+				break
+			}
+			time.Sleep(50 * time.Millisecond)
+		}
+
+	}
+}