Controlling a GPIO input/output pin

In this guide, we are using periph.io, a library for peripheral I/O in Go, to set one of the Raspberry Pi’s General Purpose I/O (GPIO) pins to a logical high (3.3V) or low (0V) signal.

periph.io supports the Raspberry Pi 3 and Raspberry Pi 4, starting with version v3.6.4.

Connect GPIO pins based on pinout

To verify the code is doing what we expect, let’s connect a multimeter as per pinout.xyz’s pinout:

We need to set the multimeter to “Voltage measurement, DC (direct current)”.

Setting an output pin signal

To set the pin high and low, alternatingly, with a 5 second frequency, we will be using the hello-gpio program, which is a slightly modified version of the example at periph.io/device/led:

package main

import (


func doGPIO() error {
	log.Printf("Loading periph.io drivers")
	// Load periph.io drivers:
	if _, err := host.Init(); err != nil {
		return err
	log.Printf("Toggling GPIO forever")
	t := time.NewTicker(5 * time.Second)
	for l := gpio.Low; ; l = !l {
		log.Printf("setting GPIO pin number 18 (signal BCM24) to %v", l)
		// Lookup a pin by its location on the board:
		if err := rpi.P1_18.Out(l); err != nil {
			return err
	return nil

func main() {
	if err := doGPIO(); err != nil {

Install the program on your Raspberry Pi using gokrazy (see Quickstart):

gokr-packer \
  -update=yes \
  github.com/gokrazy/hello \
  github.com/gokrazy/breakglass \
  github.com/gokrazy/serial-busybox \

…and wait a few seconds for it to reboot.

At this point, we should be able to see the high/low signal on the multimeter, alternating between 3.3V (high) and 0V (low) every 5 seconds: