Display a simple pattern on a SH1122 OLED display

sh1122.go

package main

import (
	"time"

	"periph.io/x/conn/v3/gpio"
	"periph.io/x/conn/v3/gpio/gpioreg"
	"periph.io/x/conn/v3/physic"
	"periph.io/x/conn/v3/spi"
	"periph.io/x/conn/v3/spi/spireg"
	"periph.io/x/host/v3"
)

const (
	width  = 256
	height = 64
)

func main() {

	// Initialize periph.io drivers
	_, err := host.Init()
	if err != nil {
		panic(err)
	}

	// Open the SPI port
	p, err := spireg.Open("/dev/spidev0.0")
	if err != nil {
		panic(err)
	}
	defer p.Close()

	// Connect to SPI device
	c, err := p.Connect(1*1024*1024*physic.Hertz, spi.Mode0, 8)
	if err != nil {
		panic(err)
	}

	var (
		rstPin = gpioreg.ByName("GPIO25")
		dcPin  = gpioreg.ByName("GPIO24")
		csPin  = gpioreg.ByName("GPIO23")
	)

	// Reset sequence
	if err := rstPin.Out(gpio.High); err != nil {
		panic(err)
	}
	time.Sleep(10 * time.Millisecond)
	if err := rstPin.Out(gpio.Low); err != nil {
		panic(err)
	}
	time.Sleep(10 * time.Millisecond)
	if err := rstPin.Out(gpio.High); err != nil {
		panic(err)
	}

	// Setup dc and cs pins
	if err := dcPin.Out(gpio.Low); err != nil {
		panic(err)
	}
	if err := csPin.Out(gpio.High); err != nil {
		panic(err)
	}

	// Send the provided data over the SPI connection
	send := func(b []byte, data bool) error {
		var l gpio.Level
		if data {
			l = gpio.High
		} else {
			l = gpio.Low
		}
		if err := dcPin.Out(l); err != nil {
			return err
		}
		if err := csPin.Out(gpio.Low); err != nil {
			return err
		}
		if err := c.Tx(b, make([]byte, len(b))); err != nil {
			return err
		}
		return csPin.Out(gpio.High)
	}

	// Turn the display on
	if err := send([]byte{0xaf}, false); err != nil {
		panic(err)
	}

	// Build the pattern
	b := []byte{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef}
	for i := 0; i < 9; i++ {
		b = append(b, b...)
	}

	// Send the pattern twice
	for i := 0; i < 2; i++ {
		if err := send(b, true); err != nil {
			panic(err)
		}
	}

	time.Sleep(1 * time.Second)
}