2.2.4 Reed Switch Module

Introduction

In this project, we will learn about the reed switch, which is an electrical switch that operates by means of an applied magnetic field.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Raphael Kit	337	Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
GPIO Extension Board	BUY
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
LED	BUY
Reed Switch Module	BUY

Schematic Diagram

T-Board Name	physical	wiringPi	BCM
GPIO17	Pin 11	0	17
GPIO27	Pin 13	2	27
GPIO22	Pin 15	3	22

Experimental Procedures

Step 1: Build the circuit.

Step 2: Go to the folder of the code.

cd ~/raphael-kit/nodejs/

Step 3: Run the code.

sudo node reed_switch_module.js

The green LED will light up when the code is run. If a magnet is placed close to the reed switch module, the red LED lights up; take away the magnet and the green LED lights up again.

Code

const Gpio = require('pigpio').Gpio;

const led1 = new Gpio(22, {mode: Gpio.OUTPUT});
const led2 = new Gpio(27, {mode: Gpio.OUTPUT});

const reedSwitch = new Gpio(17, {
    mode: Gpio.INPUT,
    pullUpDown: Gpio.PUD_DOWN,
    edge: Gpio.EITHER_EDGE
});

reedSwitch.on('interrupt', (level) => {
    led1.digitalWrite(level);
    led2.digitalWrite(!level);
});

Code Explanation

const Gpio = require('pigpio').Gpio;

const reedSwitch = new Gpio(17, {
    mode: Gpio.INPUT,
    pullUpDown: Gpio.PUD_DOWN,
    edge: Gpio.EITHER_EDGE
});

Import the pigpio module, create a ReedPin object to control the IO port, set it to input mode, pull down (initially low level), and set an interrupt.

const led1 = new Gpio(22, {mode: Gpio.OUTPUT});
const led2 = new Gpio(27, {mode: Gpio.OUTPUT});

Create two objects led1, led2 to control the IO ports Gpio22 and Gpio27, and set them to output mode.

reedSwitch.on('interrupt', (level) => {
    led1.digitalWrite(level);
    led2.digitalWrite(!level);
});

When the interrupt is triggered, write the same level to led1, and write the opposite level to led2.

Phenomenon Picture