Websocket Server
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This example will instantiate a web server running on port 8888 with support for WebSockets enabled. The example HTML file will open a websocket and send data back and forth to Serial Port of PremierWave XN.
Prerequisites
1) Requires PySerial module - already included with the Python supported firmware
2) Download Tornado (http://tornadoweb.org) and do a manual installation.
3) Extract the "tornado" directory from the tarball (tar.gz) and upload it via FTP to the PremierWave User Filesystem partition.
Sample Code
Upload file websocket_server.py (code shown in-line) via FTP to the PremierWave User Filesystem partition.
import tornado.ioloop
import tornado.web
import tornado.websocket
import serial
import time
import threading
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.render("websocketexample.html")
class WSHandler(tornado.websocket.WebSocketHandler):
connections = []
def open(self):
print "WebSocket opened"
self.connections.append(self)
def on_message(self, message):
for conn in SerialPort.ports:
conn.writer(message)
def on_close(self):
print "WebSocket closed"
self.connections.remove(self)
class SerialPort():
ports = []
def __init__(self, serial_instance):
self.serial = serial_instance
self.ports.append(self)
def start(self):
self.thread_read = threading.Thread(target=self.reader)
self.thread_read.start()
def reader(self):
while True:
buffer = ''
buffer = ser.read(ser.inWaiting())
if buffer:
for conn in WSHandler.connections:
conn.write_message(buffer)
time.sleep(0.5)
def writer(self, data):
self.serial.write(str(data))
application = tornado.web.Application([
(r"/", MainHandler),
(r"/websocket",WSHandler),
])
if __name__ == "__main__":
ser = serial.Serial('/dev/ttyS1')
ser.timeout = 0
s = SerialPort(ser)
s.start()
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
Sample HTML File
Upload the HTML file provided inline below (websocket_server.html) via FTP to the PremierWave user file system partition.
<head>
<title>Web to serial</title>
<!-- <script src="js/jquery-1.8.3.min.js"></script> -->
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script>
var ws = new WebSocket("ws://"+location.hostname+":"+location.port+"/websocket");
ws.onopen = function() {
ws.send("Hello, world");
};
ws.onmessage = function (evt) {
$('#output').val($('#output').val()+evt.data);
};
var runningLen = 0;
var interval;
function newText(){
var form = document.getElementById("textInput");
var len = form.value.length;
if (len > runningLen) {
ws.send(form.value.substring(runningLen));
runningLen = len;
} else if (len < runningLen) {
runningLen = len;
};
}
function addTextAreaCallback(textArea, callback, delay) {
var timer = null;
textArea.onkeyup = function() {
if (timer) {
window.clearTimeout(timer);
}
timer = window.setTimeout( function() {
timer = null;
callback();
}, delay);
};
textArea = null;
}
$(document).ready(function() {
addTextAreaCallback(document.getElementById("textInput"), newText,500);
});
</script>
</head>
<body>
<div id="mainbody" style="background-color:#FFFFFF;margin-left:auto;margin-right:auto;">
<textarea id="textInput" rows="10" cols="50"></textarea> Text to send to serial port
<textarea id="output" rows="10" cols="50" readonly></textarea> Text from serial port
</div>
</body>
</html>
