Custom TTN uplink formatter for Seeed SenseCAP T1000-E LoRaWAN+Sensors demo

t1000_e_sensors_ttn_uplink_formatter.js

/**
 * TTN V3 uplink decoder for payloads that look like:
 *   00 8B 00 64 FC 2D FF E4 00 04
 * byte‑by‑byte:
 *   0‑1  int16  temperature × 0.1 °C   (big‑endian, signed)
 *   2     uint8 lux (raw; 0‑255)
 *   3     uint8 battery % (0‑100)
 *   4‑5  int16  accel‑X raw   (±32768 counts ≙ ±2 g) 
 *   6‑7  int16  accel‑Y raw
 *   8‑9  int16  accel‑Z raw
 *
 * Accelerometer counts are scaled to g by ÷ 16384
 * See: https://github.com/Seeed-Studio/Seeed-Tracker-T1000-E-for-LoRaWAN-dev-board/tree/a2a0d1b48007b1fc7cf1eea90a439d5b5aff112a/apps/examples/07_lorawan_sensor
 */
function decodeUplink(input) {
  const bytes = input.bytes;
  const errors = [];

  if (!bytes || bytes.length < 10) {
    errors.push("Payload too short – expected 10 bytes");
    return { data: {}, warnings: [], errors };
  }

  // helper: signed 16‑bit from two bytes
  const s16 = (hi, lo) => {
    let v = (hi << 8) | lo;
    return v & 0x8000 ? v - 0x10000 : v;
  };

  const tempRaw   = s16(bytes[0], bytes[1]);          // 0.1 °C
  const lux       = bytes[2];
  const battery   = bytes[3];

  const axRaw     = s16(bytes[4], bytes[5]);
  const ayRaw     = s16(bytes[6], bytes[7]);
  const azRaw     = s16(bytes[8],  bytes[9]);

  const data = {
    temperature_c: +(tempRaw / 10).toFixed(1),
    temperature_f: +((tempRaw / 10) * 9 / 5 + 32).toFixed(1),

    lux,
    battery_pct: battery,

    accel_x_g: +(axRaw / 16384).toFixed(5),
    accel_y_g: +(ayRaw / 16384).toFixed(5),
    accel_z_g: +(azRaw / 16384).toFixed(5),
  };

  return { data, warnings: [], errors };
}