gpioLogger.js

#!/usr/bin/env node
'use strict';

var request = require('request'),
    fs = require('fs'),
    config = require('./config'),
    Gpio = require('onoff').Gpio;

Array.prototype.hasValue = function(value) {
  var i;
  for (i=0; i<this.length; i++) { if (this[i] === value) return true; }
  return false;
};

/*
 * send value to the middleware
 *
 */
function sendValue(sensorValue, url, callback) {    
    
    request.post(
        url,
        { form: { value: parseFloat(sensorValue) } },
        function (error, response, body) {
            if (!error && response.statusCode == 200) {
                console.log("Data: " + sensorValue + " send to :" + url);
                typeof callback === 'function' && callback(null,body);
            }else{
                if(response){
                    console.error("Error while sending data. error:" +  error  + " Respone: " + response.statusCode);
                }else{
                    console.error("Error while sending data. Could not connect to the server. error:" +  error + " url: " + url);
                }
                typeof callback === 'function' && callback(error,null);
            }
        }
    );
} 

/*
 * read GPIO port 
 */
function readImpuls(channel){
    var debounceTimeout = channel.impulse.debounceTimeout || 0,
        edge   = channel.impulse.edge || 'rising';

    // Open Gpio port 
    var port = new Gpio(channel.impulse.gpioPort, 'in', edge, {debounceTimeout: debounceTimeout});

    // buffer for pulse
    var pulseCounter = 0;

    console.log('listening on GPIO port: ' + channel.impulse.gpioPort);
    
    // watch for changes on GPIO port, only chnages from 0 -> 1 will increase the counter
    port.watch(function(err, value) {
        if (err) {
          console.error(err);
        }
        
        pulseCounter ++;
        console.log("pulse found on: " +  channel.impulse.gpioPort + " count: " + pulseCounter);
    });
    
    // send counter to the middleware
    setInterval(function(){
        if(pulseCounter){
            // save counter to restore the count if something went wrong
            var pulseMemory = pulseCounter;
            pulseCounter = 0;

            sendValue(sensorValue, channel.url, function(err, data) {
                if(err){
                    pulseCounter += pulseMemory;
                }
            });
        }
    },  parseInt(channel.interval, 10) * 1000);    // write every x seconds to middleware
}

/*
 * read 1Wire sensor 
 */
function readOneWire(channel){

    setInterval(function(){
        
        fs.readFile('/sys/bus/w1/devices/' +  channel.oneWire.device + '/w1_slave' , function (err, data) {

            if (err){
                console.error(err);
                throw err;
            }
            var dataValue = data.toString();

            // Parse data, read tempature
            var sensorValue = parseFloat(dataValue.slice( dataValue.indexOf("t=") +2) / 1000);

            // sensorValue found and not in ignore list
            if(sensorValue && !channel.oneWire.ignore.hasValue(sensorValue)){
                // send data 
                console.log("channel " + channel.oneWire.device + " : " + sensorValue +"C");

                sendValue(sensorValue, channel.url);              
            }
        });
    },  parseInt(channel.interval, 10) * 1000);    // write every x seconds to middleware
}

config.channels.forEach(function(channel){
    if(channel.impulse){ 
        readImpuls(channel);
    }else if(channel.oneWire){
        readOneWire(channel);
    }else{
        console.error('Configuration error, no channel type found.');
    }
});

console.log("ready..");