f1ed809c71
- null-terminated TSV frame: V_bat, IMU (9 fields), RPM, gear - mock RPM ramps 800-8000, gear derived from RPM bands - voltage calibration offset - PROTOCOL.md documents wire format Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
1.9 KiB
1.9 KiB
Arduino-Pi Communication Protocol
Telemetry protocol for Arduino → Pi communication over UART at 115200 baud.
Design Rationale
- ASCII-based: Human-debuggable, digits are self-bounding (no accidental header spoofing)
- TSV format: Tab delimiter, predictable field count, trivial to parse, survives floating decimals
- Null-terminated:
\0(0x00) is unambiguous end-of-line, avoids CRLF headaches - 10Hz rate: ~50 bytes/line × 10Hz = 500 B/s, well under 115200 baud capacity (~4% utilization)
Telemetry Frame (Arduino → Pi)
field0\tfield1\tfield2\t...\tfieldN\0
Fields
| Index | Name | Unit | Description |
|---|---|---|---|
| 0 | V_bat | V | Battery voltage |
| 1 | Ax | g | Acceleration X |
| 2 | Ay | g | Acceleration Y |
| 3 | Az | g | Acceleration Z |
| 4 | Gx | deg/s | Angular velocity X |
| 5 | Gy | deg/s | Angular velocity Y |
| 6 | Gz | deg/s | Angular velocity Z |
| 7 | Roll | deg | Euler angle roll |
| 8 | Pitch | deg | Euler angle pitch |
| 9 | Yaw | deg | Euler angle yaw |
| 10 | RPM | RPM | Engine RPM |
| 11 | Gear | - | Gear position (0=N, 1-6) |
Example
12.45\t0.02\t-0.01\t1.00\t0.50\t-0.25\t0.10\t2.35\t-1.20\t45.80\t3500\t3\0
Stale Data Handling
When IMU data is stale, empty fields are sent to preserve field count:
12.45\t\t\t\t\t\t\t\t\t\0
Backend parses empty fields as null/NaN.
Commands (Pi → Arduino)
TBD: Command structure for configuration, calibration triggers, etc.
Versioning
Protocol changes should bump a version field or use a different frame header. Currently unversioned (v0 / development).