Datacake-decode.js

// The function must return an object, e.g. {"temperature": 22.5}
function Decoder(bytes, port) {

	var hexString = bin2HexStr(bytes);

	var decoded = rakSensorDataDecode(hexString);

	// Extract Gateway Metadata
	decoded.LORA_RSSI = (!!normalizedPayload.gateways && !!normalizedPayload.gateways[0] && normalizedPayload.gateways[0].rssi) || 0;
	decoded.LORA_SNR = (!!normalizedPayload.gateways && !!normalizedPayload.gateways[0] && normalizedPayload.gateways[0].snr) || 0;
	decoded.LORA_DATARATE = normalizedPayload.data_rate;


	// Transform Lat + Long into location
	if (decoded.hasFix == 1) {
		// if (decoded.latitude != 0.0) {
		decoded.location = "(" + decoded.latitude + "," + decoded.longitude + ")";
	}

	// Array where we store the fields that are being sent to Datacake
	var datacakeFields = []

	// take each field from decoded and convert them to Datacake format
	for (var key in decoded) {
		if (decoded.hasOwnProperty(key)) {
			datacakeFields.push({ field: key.toUpperCase(), value: decoded[key] })
		}
	}

	// forward data to Datacake
	return datacakeFields;
}

// convert array of bytes to hex string.
// e.g: 0188053797109D5900DC140802017A0768580673256D0267011D040214AF0371FFFFFFDDFC2E
function bin2HexStr(bytesArr) {
	var str = "";
	for (var i = 0; i < bytesArr.length; i++) {
		var tmp = (bytesArr[i] & 0xff).toString(16);
		if (tmp.length == 1) {
			tmp = "0" + tmp;
		}
		str += tmp;
	}
	return str;
}

// convert string to short integer
function parseShort(str, base) {
	var n = parseInt(str, base);
	return (n << 16) >> 16;
}

// convert string to triple bytes integer
function parseTriple(str, base) {
	var n = parseInt(str, base);
	return (n << 8) >> 8;
}

// convert string to Quadruple bytes integer
function parseQuadruple(str, base) {
	var n = parseInt(str, base);
	return (n << 32) >> 32;
}

// decode Hex sensor string data to object
function rakSensorDataDecode(hexStr) {
	var str = hexStr;
	var myObj = {};

	while (str.length > 4) {
		var flag = parseInt(str.substring(0, 4), 16);
		switch (flag) {
			case 0x0768:// Humidity
				myObj.humidity = parseFloat(((parseShort(str.substring(4, 6), 16) * 0.01 / 2) * 100).toFixed(1));// + "%RH";//unit:%RH
				str = str.substring(6);
				break;
			case 0x0673:// Atmospheric pressure
				myObj.barometer = parseFloat((parseShort(str.substring(4, 8), 16) * 0.1).toFixed(2));// + "hPa";//unit:hPa
				str = str.substring(8);
				break;
			case 0x0267:// Temperature
				myObj.temperature = parseFloat((parseShort(str.substring(4, 8), 16) * 0.1).toFixed(2));// + "°C";//unit: °C
				str = str.substring(8);
				break;
			case 0x0188:// GPS
				myObj.latitude = parseFloat((parseQuadruple(str.substring(4, 12), 16) * 0.000001).toFixed(6));// + "'";
				myObj.longitude = parseFloat((parseQuadruple(str.substring(12, 20), 16) * 0.000001).toFixed(6));// + "'";
				myObj.altitude = parseFloat((parseQuadruple(str.substring(20, 28), 16) * 0.01).toFixed(1));// + "m";
				str = str.substring(28);
				if ((myObj.latitude == 0.0) && (myObj.longitude == 0.0)) {
					myObj.hasFix = 0;
				} else {
					myObj.hasFix = 1;
				}
				break;
			case 0x0371:// Triaxial acceleration
				myObj.acceleration_x = parseFloat((parseShort(str.substring(4, 8), 16) * 0.001).toFixed(3));// + "g";//unit:g
				myObj.acceleration_y = parseFloat((parseShort(str.substring(8, 12), 16) * 0.001).toFixed(3));// + "g";//unit:g
				myObj.acceleration_z = parseFloat((parseShort(str.substring(12, 16), 16) * 0.001).toFixed(3));// + "g";//unit:g
				str = str.substring(16);
				break;
			case 0x0402:// air resistance
				myObj.gasResistance = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "KΩ";//unit:KΩ
				str = str.substring(8);
				break;
			case 0x0802:// Battery Voltage
				myObj.battery = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "V";//unit:V
				str = str.substring(8);
				break;
			case 0x0586:// gyroscope
				myObj.gyroscope_x = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "°/s";//unit:°/s
				myObj.gyroscope_y = parseFloat((parseShort(str.substring(8, 12), 16) * 0.01).toFixed(2));// + "°/s";//unit:°/s
				myObj.gyroscope_z = parseFloat((parseShort(str.substring(12, 16), 16) * 0.01).toFixed(2));// + "°/s";//unit:°/s
				str = str.substring(16);
				break;
			case 0x0902:// magnetometer x
				myObj.magnetometer_x = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "μT";//unit:μT
				str = str.substring(8);
				break;
			case 0x0a02:// magnetometer y
				myObj.magnetometer_y = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "μT";//unit:μT
				str = str.substring(8);
				break;
			case 0x0b02:// magnetometer z
				myObj.magnetometer_z = parseFloat((parseShort(str.substring(4, 8), 16) * 0.01).toFixed(2));// + "μT";//unit:μT
				str = str.substring(8);
				break;
			default:
				str = str.substring(7);
				break;
		}
	}

	return myObj;
}