Example: I²C temperature sensor (TMP102)

Run firmware that talks to a TMP102 over I²C on the twin. No special LabWired HAL in the firmware — normal bus reads.

What you get

Piece	Location
Device model	`configs/devices/tmp102.yaml`
Type id	`tmp102`
Default I²C address	`0x48`
Demo + e2e	`examples/esp32s3-i2c-tmp102/`

The model’s temperature register can self-drift (+0.5 °C per full read, wrap 35 °C → 20 °C) so demos exercise thresholds without external stimulus. For a sensor driven by a temperature input channel (noise + lag), see mcp9808.yaml.

1. Attach the device

Use a real system from the repo and add (or keep) the TMP102 on the I²C bus your firmware uses. Pattern:

external_devices:
  - id: "tmp102"
    type: "tmp102"
    connection: "i2c0"    # match the bus id in that system / chip
    config:
      i2c_address: 0x48

Copy field names from a working system under configs/systems/ or examples/*/system.yaml — schemas differ slightly by board family.

2. Firmware

Firmware should:

Init I²C on the pins wired in the system
Write pointer 0x00, read 2 bytes (12-bit left-justified temp, big-endian)
Print T = … on UART (or USB-serial)

The ESP32-S3 demo does this once per second and toggles a GPIO above 30 °C. See examples/esp32s3-i2c-tmp102/.

3. Run / test

From the core repo (with ESP32-S3 fixtures when using the e2e test):

# End-to-end test (builds + asserts UART and GPIO)
cargo test -p labwired-core --features esp32s3-fixtures \
  --release --test e2e_i2c_tmp102

Or run your own ELF:

labwired run --firmware path/to/firmware.elf --system path/to/system.yaml
labwired test --script path/to/smoke.yaml

Expected (demo): UART lines like T = 25.00 C, then rising temperatures as the model drifts.

4. Agent path

labwired_describe id=tmp102
# wire diagram on a board that has I2C
labwired_run → labwired_verify (serial contains "T =" or register checks)


Add your own sensor	Onboard a part
MCP9808 (SimInput temperature)	`configs/devices/mcp9808.yaml`
SPI example direction	ADXL345 SPI device · Onboard a part