This post is basically to support the below video, I have posted in Youtube regarding one of my fun projects that I'm working on my Raspberry Pi.
Project - Raspberry Pi Servo Motor Controller using Node JS
Project is to build a small Node JS application that runs a web socket server in my Raspberry Pi, which then enable my iPhone to connect to the web server using an ordinary browser like Safari through Web Socket Protocol to send its Gyroscope data back to Raspberry Pi. Then web server will use this data to send PWM (Pulse Width Modulation) signals to it's selected GPIO pins connected to a servo motor.
By doing this I'll be able to control the servo motor using my iPhone over a LAN.
I know there are many ways you can achieve the same results, But I wanted use these selected technologies, so I can learn them better (and have FUN of doing it). I haven't used any Servo Controller Shields in this project either. Enjoy the video below.
Here is the code :
Server : app.js
Client Page : ws.html
Schematic for this project is fairly simple on, but I'll post is anyway,Project - Raspberry Pi Servo Motor Controller using Node JS
Project is to build a small Node JS application that runs a web socket server in my Raspberry Pi, which then enable my iPhone to connect to the web server using an ordinary browser like Safari through Web Socket Protocol to send its Gyroscope data back to Raspberry Pi. Then web server will use this data to send PWM (Pulse Width Modulation) signals to it's selected GPIO pins connected to a servo motor.
By doing this I'll be able to control the servo motor using my iPhone over a LAN.
I know there are many ways you can achieve the same results, But I wanted use these selected technologies, so I can learn them better (and have FUN of doing it). I haven't used any Servo Controller Shields in this project either. Enjoy the video below.
Here is the code :
Server : app.js
1: var express = require('express');
2: var app = express();
3: var server = require('http').createServer(app);
4: var fs = require('fs');
5: var WebSocketServer = require('websocket').server;
6: var piblaster = require("pi-blaster.js");
7:
8:
9: var clients = [ ];
10:
11: //Getting request from browser
12: //and send response back
13: app.get ('/', function(req, res){
14:
15: fs.readFile('ws.html', 'utf8', function(err, text){
16: res.send(text);
17: });
18: });
19:
20: //Listening to Port 1337 for incoming messages
21: server.listen(1337, function (){
22: console.log((new Date()) + " Server is listening on port 1337... ");
23: });
24:
25: websock = new WebSocketServer({
26: httpServer: server
27: });
28:
29: //WebSocket Server
30:
31: websock.on('request', function(request) {
32:
33: console.log((new Date()) + ' Connection from origin ' + request.origin + '.');
34:
35: var connection = request.accept(null, request.origin);
36:
37: console.log((new Date()) + ' Connection accepted.');
38:
39: //Incoming Data handling
40: connection.on('message', function(message) {
41:
42: console.log('Data: ' + message.utf8Data);
43:
44: var data = message.utf8Data;
45: data = data.slice(1,3);
46:
47: // If incoming data is > 2 send a signal to pin 17
48: // Set GPIO pin 17 to a PWM of 24%
49: // Truns the Servo to it's right
50: if (Number(data)>2){
51: piblaster.setPwm(17, 0.24);
52: }
53:
54: // If incoming data is > 2 send a signal to pin 17
55: // Set GPIO pin 17 to a PWM of 6%
56: // Truns the Servo to it's left
57: if (Number(data)<(-2)){
58: piblaster.setPwm(17, 0.06);
59: }
60:
61: // If incoming data is > 2 send a signal to pin 17
62: // Set GPIO pin 17 to a PWM of 15%
63: // Truns the Servo to it's center position
64: if (Number(data)==0){
65: piblaster.setPwm(17, 0.15);
66: }
67:
68: });
69:
70: connection.on('close', function (connection){
71: //close connection
72: piblaster.setPwm(17, 0);
73: });
74:
75: function closePin(){
76: piblaster.setPwm(17, 0);
77: }
78:
79: });
Client Page : ws.html
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>WebSockets - Simple chat</title>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
</head>
<body>
<div id="content"></div>
<div>
<span id="status">Connecting...</span>
</div>
<script type="text/javascript">
$(function () {
// Position Variables
var x = 0;
var y = 0;
var z = 0;
// Speed - Velocity
var vx = 0;
var vy = 0;
var vz = 0;
// Acceleration
var ax = 0;
var ay = 0;
var az = 0;
var ai = 0;
var arAlpha = 0;
var arBeta = 0;
var arGamma = 0;
var delay = 200;
var vMultiplier = 0.01;
var alpha = 0;
var alpha = 0;
var beta = 0;
var gamma = 0;
var content = $('#content');
var status = $('#status');
// if user is running mozilla then use it's built-in WebSocket
window.WebSocket = window.WebSocket || window.MozWebSocket;
if (!window.WebSocket) {
content.html($('<p>', { text: 'Sorry, but your browser doesn\'t '
+ 'support WebSockets.'} ));
input.hide();
$('span').hide();
return;
}
var connection = new WebSocket('ws://'+document.domain+':1337');
connection.onopen = function () {
status.text('You are connected to ThanboPi Server.' +
'Move your device and Have Fun!!');
};
connection.onerror = function (error) {
content.html($('<p>', { text: 'Sorry, but there\'s some problem with your '
+ 'connection or the server is down.' } ));
};
if (window.DeviceMotionEvent!=undefined) {
window.ondevicemotion = function(event) {
ax = Math.round((event.accelerationIncludingGravity.x * 1));
ay = Math.round(Math.abs(event.accelerationIncludingGravity.y * 1));
az = Math.round(Math.abs(event.accelerationIncludingGravity.z * 1));
ai = Math.round(event.interval * 100) / 100;
rR = event.rotationRate;
if (rR != null) {
arAlpha = Math.round(rR.alpha);
arBeta = Math.round(rR.beta);
arGamma = Math.round(rR.gamma);
}
}
window.ondeviceorientation = function(event) {
alpha = Math.round(event.alpha);
beta = Math.round(event.beta);
gamma = Math.round(event.gamma);
}
setInterval(function() {
connection.send('x' + ax);
}, delay);
}
});
</script>
</body>
</html>
Components : RPI, Breadboard, a 1K resistor and a Basic Servo Motor
PS: If you need to know more details with regards to libraries, frameworks and hardware I'm using in this project, please ask your questions in the comment section. I would happily assist you.
