ChirpStackV4_Decoder.js

// Decode uplink function.
//
// Input is an object with the following fields:
// - bytes = Byte array containing the uplink payload, e.g. [255, 230, 255, 0]
// - fPort = Uplink fPort.
// - variables = Object containing the configured device variables.
//
// Output must be an object with the following fields:
// - data = Object representing the decoded payload.
function decodeUplink(input) {
    var decoded = {
        data:[]
    };
    var type;
    var floatNumber;

    if ( (input.bytes.length  % 5) !== 0) {
        decoded.data.push({
            type: "error",
            Value: -1
        });

        return { data: decoded }
    }

    const arrayBuffer = new ArrayBuffer(4);
    const dataView = new DataView(arrayBuffer);
    
    for(let j =0 ; j < input.bytes.length; j+=5) {
        var num =0;
        switch ( input.bytes[j]) {
            case 0:
                type = 'Temp';
                num  = 2;
                break;
            case 1:
                type = 'Humidity';
                num  = 2;
                break;
            case 2:
                type = 'CO2';
                num  = 0;
                break;
            case 3:
                type = 'TVOC';
                num  = 0;
                break;
            case 4:
                type = 'Light';
                num  = 0;
                break;
            default:
                type = 'unknown';
                break;
        }
        for (let i = 0; i < 4; i++) {
            dataView.setUint8(i, input.bytes[j+i+1]);
        }
        floatNumber = dataView.getFloat32(0, true); 
        decoded.data.push({
            type:  type,
            Value: floatNumber.toFixed(num)
        });
    }
    return { data: decoded }
}

// Encode downlink function.
//
// Input is an object with the following fields:
// - data = Object representing the payload that must be encoded.
// - variables = Object containing the configured device variables.
//
// Output must be an object with the following fields:
// - bytes = Byte array containing the downlink payload.
function encodeDownlink(input) {
  return {
    bytes: [225, 230, 255, 0]
  };
}