Hello, I am working on a project that will read in two switches and then
update a website with the status of the switches. I am new to working with
boards such as the BeagleBone Black, node.js, and socket.io. Before I get
that far I first have been trying to follow a not-so-simple tutorial that
has been full of a number of errors. I have managed to fix quite a few of
them and add some of my own code. Currently this example should blink a led
on a breadboard but also change the background color of an html page. I
have been stuck on this for a while since and have not been able to get any
further for a couple days. My problems with my js file: 1)when first
running the file after "Server running at......" I receive a line that says
"undefined" then once I press the switch it only shows 1 or 0 as it should,
I don't know why I am getting undefined. 2)When pressing the switch the led
lights the way it is supposed to but the html page does not update and I
cannot figure out what I am doing incorrectly to make the background change
when the switch is pressed. I would greatly appreciate any feedback on what
is being done incorrectly or shown corrects.
This is what my button.js file looks like:
var app = require('http').createServer(handler);
var io = require('socket.io').listen(app);
var fs = require('fs');
var url = require('url');
var path = require('path');
// runs only on beaglebone!
var b = require('bonescript');
var inputPin = "P8_19"; //switch is located on this pin
var ledPin = "P8_15"; //breadboard led is located on this pin
app.listen(2509); //listen on port 2509
console.log('Server running at http://beaglebone.local:2509/');
io.sockets.on('connection', function(socket) {
b.attachInterrupt(inputPin, true, b.CHANGE, function(inputPin, value) {
socket.emit('button_event', ((b.value == b.HIGH) ? 'white' : 'red')
);
socket.broadcast.emit('button_event', ((b.alue == b.HIGH) ? 'white'
: 'red') );
});
});
b.pinMode(ledPin, b.OUTPUT);
b.pinMode(inputPin, b.INPUT);
b.attachInterrupt(inputPin, true, b.CHANGE, buttonChange);
function buttonChange(button) {
if(button.value == b.HIGH)
state = b.HIGH;
else
state = b.LOW;
b.digitalWrite(ledPin, state);
console.log(button.value);
}
function handler(req, res) {
var uri = url.parse(req.url).pathname;
var subdir = path.join(process.cwd(), 'button');
if (uri == '/') {
loadFile('index.html', subdir, res, "text/html");
} else {
if (uri.match(/\.js$/i)) {
loadFile(uri, subdir, res, "application/javascript");
} else if (uri.match(/\.css$/i)) {
loadFile(uri, subdir, res, "text/css");
} else if (uri.match(/\.htm(.)$/i)) {
loadFile(uri, subdir, res, "text/html");
} else if (uri.match(/\.(jpg|png|ico|gif)$/i)) {
loadFile(uri, subdir, res, "binary");
} else {
loadFile(uri, subdir, res, "text/plain");
}
}
};
function loadFile(uri, subdir, res, type) {
var filename = path.join(subdir, uri);
fs.exists(filename, function(exists) {
if (!exists) {
res.writeHead(404, {
"Content-Type": "text/plain"
});
res.write("Error 404: '" + uri + "' Not Found\n");
res.end();
}else if (type == "binary") {
fs.readFile(
filename, "binary", function(err, file) {
if (err) {
res.writeHead(500, {
"Content-Type": "text/plain"
});
res.write(err + "\n");
res.end();
return;
}
res.writeHead(200);
res.write(file, "binary");
res.end();
});
} else {
fs.readFile(
filename, encoding = 'utf8', function(err, file) {
if (err) {
//res.writeHead(500, {
// "Content-Type": "text/plain"
//});
res.write(err + "\n");
res.end();
return;
}
res.writeHead(200, {
"Content-Type": type
});
res.write("" + file);
res.end();
});
}
});
};
This is what my index.html file looks like:
<html>
<head>
<script src = "/socket.io/socket.io.js" > </script>
<script type="text/javascript"
src="http://code.jquery.com/jquery-1.7.1.min.js";></script>
<script>
var socket = io.connect();
socket.on('button_event', function (data) {
console.log(data);
$("body").css("background-color", data);
});
</script>
</head>
<body>
<h1>Press the button, the page will become red!</h1>
</body>
</html>
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