Hardware setup
Logic levels
The FDO2-G2 UART is 3.0 V signalling with 3.3 V absolute maximum on those pins (data sheet §2 / §4). Your MCU UART must not drive 5 V TTL into the sensor. Use level shifters or a 3.3 V-native host (for example ESP32-S3).
UART parameters
| Parameter | Default | Notes |
|---|---|---|
| Baud | 19200 | Factory default after every power cycle |
| Data | 8 bits | |
| Parity | None | |
| Stop | 1 bit | |
| Flow control | None |
Higher baud is possible only after a successful #BAUD command (not implemented
in this driver build).
Boot delay
The module needs on the order of one second after power-up before it accepts
commands. The ESP32 example waits kFdo2G2PowerUpSettleMs (~1100 ms) before #VERS.
Connector
The data sheet references Molex 560020-0420 for the module harness. Route TX/RX/GND only after confirming pinout for your cable revision.
ESP32-S3 shipped examples (default)
The examples/esp32 apps map MCU TX → sensor RX and MCU RX ← sensor TX
on UART_NUM_1: GPIO47 (TX), GPIO21 (RX), 19200 8N1. Change the
template parameters on the Fdo2EspIdfUart<…> type alias if your board uses
different pins.
Fast versus verbose reads
#MOXY— smallest response; ideal for high-rate control loops.#MRAW— adds pressure, humidity, dphi, and intensities for diagnostics and for the documented %O₂ ratio when P tracks vent-side pressure.
Next: CMake integration →