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A simple example of continuously reading from a serial based device and using websockets to send data to all registered clients on the server.
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| # coding: utf-8 | |
| require 'sinatra' | |
| require 'sinatra-websocket' | |
| require 'serialport' | |
| set :server, 'thin' | |
| set :sockets, [] | |
| ## Setup to read from your device via serial port | |
| ser = SerialPort.new("/dev/your_device", 9600, 8, 1, SerialPort::NONE) | |
| ## Starts countously reading from Serial Port and sending data to all connected clients | |
| count = 0 | |
| rns = Array.new() | |
| EM.defer do | |
| while true do | |
| response = ser.readline("\r") | |
| response.chomp! | |
| rns << response.to_i | |
| count += 1 | |
| if count == 500 | |
| count = 0 | |
| res=Hash[rns.group_by {|x| x}.map {|k,v| [k,v.count]}] | |
| rns.clear | |
| settings.sockets.each{|s| s.send(res.to_s) } | |
| end | |
| end | |
| end | |
| ## On first request, send erb template, then we just manage sockets | |
| get '/' do | |
| if !request.websocket? | |
| erb :index | |
| else | |
| request.websocket do |ws| | |
| ws.onopen do | |
| settings.sockets << ws | |
| end | |
| ws.onclose do | |
| settings.sockets.delete(ws) | |
| end | |
| end | |
| end | |
| end | |
| __END__ | |
| @@ index | |
| <html> | |
| <body> | |
| <h1 class="text-align:center">Serial Data from Source</h1> | |
| <div id="data"></div> | |
| </body> | |
| <script type="text/javascript"> | |
| window.onload = function(){ | |
| (function(){ | |
| var show = function(el){ | |
| return function(msg){ el.innerHTML = msg + '<br />' + el.innerHTML; } | |
| }(document.getElementById('data')); | |
| var ws = new WebSocket('ws://' + window.location.host + window.location.pathname); | |
| ws.onmessage = function(m) { show(m.data); }; | |
| })(); | |
| } | |
| </script> | |
| </html> |
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| void setup() { | |
| // initialize the serial communication: | |
| Serial.begin(9600); | |
| // send the value of analog input 0 (electronic noise) | |
| randomSeed(analogRead(A0)); | |
| } | |
| void loop() { | |
| //Send a random integer from 1 to 10 to serial port | |
| Serial.println(random(1,11)); | |
| } |
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