TTN Smart Sensor (Ellenex)

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function decodeUplink(input) { switch (input.fPort) { case 15: // return error if length of Bytes is not 8 if (input.bytes.length != 8) { return { errors: ['Invalid uplink payload: length is not 8 byte'], }; } if(input.bytes[0] == 0x80) { //Used for FMS2 let primarySense = readHex2bytes(input.bytes[1], input.bytes[2]); //Pressure for FMS2 //Does not account for negative numbers let pulseCounter = input.bytes[3] << 24 | input.bytes[4] << 16 | input.bytes[5] << 8 | input.bytes[6]; }else if(input.bytes[0] == 0x82) { //TODO } //let secondarySense = readHex2bytes(input.bytes[5], input.bytes[6]); let batteryVoltage = input.bytes[7] * 0.1; return { // Decoded data data: { primarySense: primarySense, pulseCounter: pulseCounter, batteryVoltage: +batteryVoltage.toFixed(1), }, }; default: return { errors: ['Unknown FPort: please use fPort 1'], }; } } /* * The readHex2bytes function is to decode a signed 16-bit integer * represented by 2 bytes. */ function readHex2bytes(byte1, byte2) { let result = (byte1 << 8) | byte2; // merge the two bytes // check whether input is signed as a negative number // by checking whether significant bit (leftmost) is 1 let negative = byte1 & 0x80; // process negative value if (negative) { //result = ~(0xFFFF0000 | (result - 1)) * (-1); // minus 1 and flip all bits result = result - 0x10000; } return result; }