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2.2.6 Speed Sensor Module¶

Introduction¶

In this project, we will learn the use of the speed sensor module. A Speed sensor module is a type of tachometer that is used to measure the speed of a rotating object like a motor.

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
Speed Sensor Module	-

Schematic Diagram¶

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 speed_sensor_module.js

After the code runs, the green LED will light up. If you place an obstacle in the gap of the speed sensor module, the “light blocked” will be printed on the screen and the red LED will be lit. Remove the obstacle and the green LED will light up again.

Code

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

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

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

speedPin.on('interrupt', (level) => {
    if (level) {
        console.log("Light was blocked");
    }
    Rpin.digitalWrite(level);
    Gpin.digitalWrite(!level);
});

process.on('SIGINT', function () {
    Rpin.digitalWrite(0);
    Gpin.digitalWrite(0);
    process.exit();
});

Code Explanation

The code of this example is almost the same as 2.1.5 Tilt Switch, so no need to repeat it.

Phenomenon Picture¶