라즈베리파이 3색 LED 제어하기 (feat node.js)

 

node.js를 사용해서 LED와 같은 다양한 장치를 쉽게 제어할 수 있습니다.

 

node.js 개념이 궁금하시다면?

https://gusdnr69.tistory.com/32?category=763917

node.js 란? 🤷‍♂️

 

 

soketio를 사용하는 방법도 있지만, 기본적인 방법을 우선 설명드리겠습니다.

 

3색 LED와 같은 경우 2가지가 있습니다.  커먼 캐소드 방식과 커먼 애노드 방식입니다. 각각 긴 단자를 gnd나 5v에 연결하시면 됩니다.

 

커먼캐소드 코드입니다.

var http = require('http').createServer(handler); //require http server, and create server with function handler()
var fs = require('fs'); //require filesystem module
var io = require('socket.io')(http) //require socket.io module and pass the http object (server)
var Gpio = require('pigpio').Gpio, //include pigpio to interact with the GPIO
ledRed = new Gpio(4, {mode: Gpio.OUTPUT}), //use GPIO pin 4 as output for RED
ledGreen = new Gpio(17, {mode: Gpio.OUTPUT}), //use GPIO pin 17 as output for GREEN
ledBlue = new Gpio(27, {mode: Gpio.OUTPUT}), //use GPIO pin 27 as output for BLUE
redRGB = 0, //set starting value of RED variable to off (0 for common cathode)
greenRGB = 0, //set starting value of GREEN variable to off (0 for common cathode)
blueRGB = 0; //set starting value of BLUE variable to off (0 for common cathode)

//RESET RGB LED
ledRed.digitalWrite(0); // Turn RED LED off
ledGreen.digitalWrite(0); // Turn GREEN LED off
ledBlue.digitalWrite(0); // Turn BLUE LED off

http.listen(8080); //listen to port 8080

function handler (req, res) { //what to do on requests to port 8080
  fs.readFile(__dirname + '/public/rgb.html', function(err, data) { //read file rgb.html in public folder
    if (err) {
      res.writeHead(404, {'Content-Type': 'text/html'}); //display 404 on error
      return res.end("404 Not Found");
    }
    res.writeHead(200, {'Content-Type': 'text/html'}); //write HTML
    res.write(data); //write data from rgb.html
    return res.end();
  });
}

io.sockets.on('connection', function (socket) {// Web Socket Connection
  socket.on('rgbLed', function(data) { //get light switch status from client
    console.log(data); //output data from WebSocket connection to console

    //for common cathode RGB LED 0 is fully off, and 255 is fully on
    redRGB=parseInt(data.red);
    greenRGB=parseInt(data.green);
    blueRGB=parseInt(data.blue);

    ledRed.pwmWrite(redRGB); //set RED LED to specified value
    ledGreen.pwmWrite(greenRGB); //set GREEN LED to specified value
    ledBlue.pwmWrite(blueRGB); //set BLUE LED to specified value
  });
});

process.on('SIGINT', function () { //on ctrl+c
  ledRed.digitalWrite(0); // Turn RED LED off
  ledGreen.digitalWrite(0); // Turn GREEN LED off
  ledBlue.digitalWrite(0); // Turn BLUE LED off
  process.exit(); //exit completely
});

 

커먼 애노드코드입니다.

var http = require('http').createServer(handler); //require http server, and create server with function handler()
var fs = require('fs'); //require filesystem module
var io = require('socket.io')(http) //require socket.io module and pass the http object (server)
var Gpio = require('pigpio').Gpio, //include pigpio to interact with the GPIO
ledRed = new Gpio(4, {mode: Gpio.OUTPUT}), //use GPIO pin 4 as output for RED
ledGreen = new Gpio(17, {mode: Gpio.OUTPUT}), //use GPIO pin 17 as output for GREEN
ledBlue = new Gpio(27, {mode: Gpio.OUTPUT}), //use GPIO pin 27 as output for BLUE
redRGB = 255, //set starting value of RED variable to off (255 for common anode)
greenRGB = 255, //set starting value of GREEN variable to off (255 for common anode)
blueRGB = 255; //set starting value of BLUE variable to off (255 for common anode)

//RESET RGB LED
ledRed.digitalWrite(1); // Turn RED LED off
ledGreen.digitalWrite(1); // Turn GREEN LED off
ledBlue.digitalWrite(1); // Turn BLUE LED off

http.listen(8080); //listen to port 8080

function handler (req, res) { //what to do on requests to port 8080
  fs.readFile(__dirname + '/public/rgb.html', function(err, data) { //read file rgb.html in public folder
    if (err) {
      res.writeHead(404, {'Content-Type': 'text/html'}); //display 404 on error
      return res.end("404 Not Found");
    }
    res.writeHead(200, {'Content-Type': 'text/html'}); //write HTML
    res.write(data); //write data from rgb.html
    return res.end();
  });
}

io.sockets.on('connection', function (socket) {// Web Socket Connection
  socket.on('rgbLed', function(data) { //get light switch status from client
    console.log(data); //output data from WebSocket connection to console

    //for common anode RGB LED  255 is fully off, and 0 is fully on, so we have to change the value from the client
    redRGB=255-parseInt(data.red);
    greenRGB=255-parseInt(data.green);
    blueRGB=255-parseInt(data.blue);

    console.log("rbg: " + redRGB + ", " + greenRGB + ", " + blueRGB); //output converted to console

    ledRed.pwmWrite(redRGB); //set RED LED to specified value
    ledGreen.pwmWrite(greenRGB); //set GREEN LED to specified value
    ledBlue.pwmWrite(blueRGB); //set BLUE LED to specified value
  });
});

process.on('SIGINT', function () { //on ctrl+c
  ledRed.digitalWrite(1); // Turn RED LED off
  ledGreen.digitalWrite(1); // Turn GREEN LED off
  ledBlue.digitalWrite(1); // Turn BLUE LED off
  process.exit(); //exit completely
});

 

write함수의 사용법이 조금 다른 것이 특징입니다. 

 

아래 링크에 더욱 자세하게 설명되어있으니 참고하시면 좋을 것 같습니다. 

화이팅 :) 

 

참고자료:https://www.w3schools.com/nodejs/nodejs_raspberrypi_rgb_led_websocket.asp

Node.js Raspberry Pi RGB LED and WebSocket