Payload function corresponding to the GROVE_CO2.ino Sketch

decoder.js

function Decoder(bytes, port) {
  // bytes is of type Buffer.
  'use strict';
  var TEMPSENSOR_ID,
    HUMISENSOR_ID,
    PRESSURESENSOR_ID,
    LUXSENSOR_ID,
    UVSENSOR_ID,
    PM10_ID,
    PM25_ID,
    CO2_ID;
  switch (port) {
    case 1:
        TEMPSENSOR_ID = '';
        HUMISENSOR_ID = '';
        PRESSURESENSOR_ID = '';
        LUXSENSOR_ID = '';
        UVSENSOR_ID = '';
        PM10_ID = '';
        PM25_ID = '';
        CO2_ID = '';
      break;
    default:
      throw new Error('No configured sensor IDs for uplink on port: ' + port);
  }

  var bytesToInt = function (bytes) {
    var i = 0;
    for (var x = 0; x < bytes.length; x++) {
      i |= +(bytes[x] << (x * 8));
    }
    return i;
  };

  var uint8 = function (bytes) {
    if (bytes.length !== uint8.BYTES) {
      throw new Error('int must have exactly 1 byte');
    }
    return bytesToInt(bytes);
  };
  uint8.BYTES = 1;

  var uint16 = function (bytes) {
    if (bytes.length !== uint16.BYTES) {
      throw new Error('int must have exactly 2 bytes');
    }
    return bytesToInt(bytes);
  };
  uint16.BYTES = 2;

  var humidity = function (bytes) {
    if (bytes.length !== humidity.BYTES) {
      throw new Error('Humidity must have exactly 2 bytes');
    }

    var h = bytesToInt(bytes);
    return h / 1e2;
  };
  humidity.BYTES = 2;

  var decode = function (bytes, mask, names) {

    var maskLength = mask.reduce(function (prev, cur) {
      return prev + cur.BYTES;
    }, 0);
    if (bytes.length < maskLength) {
      throw new Error('Mask length is ' + maskLength + ' whereas input is ' + bytes.length);
    }

    names = names || [];
    var offset = 0;
    return mask
      .map(function (decodeFn) {
        var current = bytes.slice(offset, offset += decodeFn.BYTES);
        return decodeFn(current);
      })
      .reduce(function (prev, cur, idx) {
        prev[names[idx] || idx] = cur;
        return prev;
      }, {});
  };

  var bytesToSenseBoxJson = function (bytes) {
    var json;

    try {
      json = decode(bytes,
        [                 
        uint16,
        humidity,
        uint16,
        uint8,
        uint16,
        uint8,
        uint16,
        uint16,
        uint16,
        uint16
        ],
        [           
        TEMPSENSOR_ID,
        HUMISENSOR_ID,
        PRESSURESENSOR_ID,
        LUXSENSOR_ID + '_mod',
        LUXSENSOR_ID + '_times',
        UVSENSOR_ID + '_mod',
        UVSENSOR_ID + '_times',
        PM10_ID,
        PM25_ID,
        CO2_ID
        ]);

      //temp
      json[TEMPSENSOR_ID] = parseFloat(((json[TEMPSENSOR_ID] / 771) - 18).toFixed(1));

      //hum
      json[HUMISENSOR_ID] = parseFloat(json[HUMISENSOR_ID].toFixed(1));

      // lux
      json[LUXSENSOR_ID] = (json[LUXSENSOR_ID + '_times'] * 255) + json[LUXSENSOR_ID + '_mod'];
      delete json[LUXSENSOR_ID + '_times'];
      delete json[LUXSENSOR_ID + '_mod'];

      // uv
      json[UVSENSOR_ID] = (json[UVSENSOR_ID + '_times'] * 255) + json[UVSENSOR_ID + '_mod'];
      delete json[UVSENSOR_ID + '_times'];
delete json[UVSENSOR_ID + '_mod'];
      // pressure
      if (json[PRESSURESENSOR_ID] !== '0') {
        json[PRESSURESENSOR_ID] = parseFloat(((json[PRESSURESENSOR_ID] / 81.9187) + 300).toFixed(1));
      } else {
        delete json[PRESSURESENSOR_ID];
      }

 
      // rain 

      // pm10
      json[PM10_ID] = parseFloat((json[PM10_ID] / 10).toFixed(1));
      // pm25
      json[PM25_ID] = parseFloat((json[PM25_ID] / 10).toFixed(1));

      json[CO2_ID] = parseFloat((json[CO2_ID] / 10).toFixed(1));


    } catch (e) {
      json = { payload: bytes };
    }

    return json;
  };

  return bytesToSenseBoxJson(bytes);
}