Overview

GPIO pins can be leveraged to detect motion via a PIR (Passive/Pyroelectric InfraRed sensor), similar to reading button presses.

The gpio.PinIn.WaitForEdge() function permits a edge detection without a busy loop.

Learn more

PIR tutorial on Adafruit that explains the physics behind the sensor
PIR on Wikipedia

Example

package main

import (
    "fmt"
    "log"

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

func main() {
    // Load all the drivers:
    if _, err := host.Init(); err != nil {
        log.Fatal(err)
    }

    // Lookup a pin by its number:
    p, err := gpioreg.ByName("16")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("%s: %s\n", p, p.Function())

    // Set it as input.
    if err = p.In(gpio.PullNoChange, gpio.RisingEdge); err != nil {
        log.Fatal(err)
    }

    // Wait for edges as detected by the hardware.
    for {
        p.WaitForEdge(-1)
        if p.Read() == gpio.High {
          fmt.Printf("You moved!\n")
        }
    }
}

This example uses basically no CPU: the WaitForEdge() leverages the edge detection provided by the kernel, unlike other Go hardware libraries.

Buying

Adafruit: adafruit.com/?q=motion%20pir
Aliexpress: aliexpress.com/wholesale?SearchText=hc-sr501
Amazon: amazon.com/s?field-keywords=hc-sr501
Pimoroni: shop.pimoroni.com/?q=motion%20pir
SeeedStudio: seeedstudio.com/s/pir%20motion.html

The periph authors do not endorse any specific seller. These are only provided for your convenience.