# Trikke Motion Telemetry Logger

Prototype v0 firmware for a Seeed Studio XIAO ESP32-C3 with an ADXL345
accelerometer and L3G4200D gyroscope on a shared I2C bus.

This milestone does four things:

1. Detects and verifies both sensors by their identification registers.
2. Configures each sensor for 100 Hz raw acquisition.
3. Emits timestamped, sensor-native raw readings over the XIAO USB connection.
4. Maps both sensors into a shared enclosure coordinate frame for validation.

BLE transport and phone-side storage come after the wired sensor path is proven.

## Wiring

| Signal | XIAO pin | ESP32-C3 GPIO |
| --- | --- | --- |
| SDA | D4 | GPIO6 |
| SCL | D5 | GPIO7 |
| Sensor power | 3V3 | — |
| Sensor ground | GND | — |

Both breakouts share SDA, SCL, 3V3, and GND. The firmware checks both possible
7-bit I2C addresses for each device:

- ADXL345: `0x53` or `0x1D`; expected `DEVID` is `0xE5`.
- L3G4200D: `0x69` or `0x68`; expected `WHO_AM_I` is `0xD3`.

## Sensor configuration

- ADXL345: 100 Hz output rate, full-resolution mode, +/-8 g. Nominal scale is
  3.9 mg/LSB.
- L3G4200D: 100 Hz output rate, 25 Hz bandwidth, +/-500 dps. Nominal scale is
  17.5 mdps/LSB.

The enclosure coordinate frame is:

- +X points right in the reference photograph.
- +Y points toward the top of the enclosure.
- +Z points out of the board toward the enclosure cover.

The L3G4200D already matches that frame. The ADXL345 mapping is:

```text
enclosure X =  native Y
enclosure Y = -native X
enclosure Z =  native Z
```

No calibration, filtering, or sensor fusion is performed yet.

## Build and flash

ESP-IDF 6.0.2 is installed at:

```text
/Users/jay/.espressif/v6.0.2/esp-idf
```

For each new terminal:

```sh
source /Users/jay/.espressif/v6.0.2/esp-idf/export.sh
idf.py build
idf.py -p /dev/cu.usbmodem1134101 flash monitor
```

Exit the serial monitor with `Ctrl-]`.

## USB output

After startup metadata, records use CSV:

```text
sequence,timestamp_us,accel_x_raw,accel_y_raw,accel_z_raw,gyro_x_raw,gyro_y_raw,gyro_z_raw,accel_native_x_raw,accel_native_y_raw,accel_native_z_raw,gyro_native_x_raw,gyro_native_y_raw,gyro_native_z_raw
```

`timestamp_us` is the ESP32-C3 monotonic microsecond timer since boot. The axes
in the first six sample columns use the enclosure frame above. The appended native
columns are temporary diagnostics for the coordinated orientation test.