Function decodeTelemetry

depot/console/src/lib/protocol.ts:225–388

(data: ArrayBuffer)

 * Decode telemetry from 120-byte binary format.
 */
export function decodeTelemetry(data: ArrayBuffer): DecodedTelemetry | null {
  const view = new DataView(data);

  // Expect exactly 120 bytes
  if (data.byteLength < 120) {
    return null;
  }

  const msgType = view.getUint8(0);
  if (msgType !== MSG_TELEMETRY) {
    return null;
  }

  // Parse header
  const mode = view.getUint8(1) as Mode;
  const sequence = view.getUint16(2, true);
  // System metrics [4-6], reserved [7]
  const cpu_percent = view.getUint8(4);
  const mem_percent = view.getUint8(5);
  const disk_percent = view.getUint8(6);

  // Pose (3x f64 = 24 bytes) [8-31]
  const poseX = view.getFloat64(8, true);
  const poseY = view.getFloat64(16, true);
  const poseTheta = view.getFloat64(24, true);

  // Battery voltage + system current [32-39]
  // New format: f32 voltage [32-35] + f32 current [36-39]
  // Old format: f64 voltage [32-39] (no current)
  // Detect by checking if f32 read produces a sane voltage (0-100V range)
  const voltageF32 = view.getFloat32(32, true);
  const isNewFormat = voltageF32 > 0 && voltageF32 < 100;
  const batteryVoltage = isNewFormat ? voltageF32 : view.getFloat64(32, true);
  const systemCurrent = isNewFormat ? view.getFloat32(36, true) : 0;

  // Timestamp [40-47]
  const timestampLow = view.getUint32(40, true);
  const timestampHigh = view.getUint32(44, true);
  const timestamp_us = timestampLow + timestampHigh * 0x100000000;

  // Commanded velocity [48-55]
  const cmdLinear = view.getFloat32(48, true);
  const cmdAngular = view.getFloat32(52, true);

  // Measured velocity [56-63]
  const measLinear = view.getFloat32(56, true);
  const measAngular = view.getFloat32(60, true);

  // Acceleration [64-71]
  const accelLinear = view.getFloat32(64, true);
  const accelAngular = view.getFloat32(68, true);

  // Motor temps (4x f32 = 16 bytes) [72-87]
  const motor_temps: [number, number, number, number] = [
    view.getFloat32(72, true),
    view.getFloat32(76, true),
    view.getFloat32(80, true),
    view.getFloat32(84, true),