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HardFOC driver

FDO2 Driver

A C++17 driver for the PyroScience FDO2-G2 optical oxygen sensor. It identifies the module, measures oxygen partial pressure and temperature, reads the raw optical, pressure and humidity data and decodes the status and error codes, on any MCU with a UART.

Quickstart API guide Source on GitHub

The driver has no platform code. You give it a small class that writes bytes to a UART and returns one reply line; it does the rest: the ASCII commands, reply parsing, unit scaling, status bits and #ERRO codes.

Optical oxygen sensor module FDO2-G2 PyroScience
Measures
Oxygen partial pressure 0 to 1000 hPa (0 to 100 % O2 at 1013 mbar), plus temperature, pressure and humidity inside the housing
Accuracy
±5 hPa at 200 hPa (10 °C to 40 °C); response time t63 under 2 s
Host interface
UART, 3.0 V levels (3.3 V absolute maximum), 19200 baud 8N1 after power-up, ASCII commands
Supply
3.3 V to 5.0 V DC (5.5 V absolute maximum); about 8 mA standby, 40 mA peak
Connector
Molex 560020-0420, four pins: GND, TXD, RXD, VCC
Driver uses
#VERS, #IDNR, #MOXY, #MRAW, #LOGO; no command that writes the module's flash

Datasheet (v5, 03/2026)

What you get

  • One object per sensor. fdo2::Driver<YourUart> sends a command and returns a typed result. See API guide.
  • Engineering units. hPa, °C, mbar, mV and %RH, scaled from the module's integer fields, and volume percent O2 from the internal pressure sensor. See UART protocol.
  • Status you cannot miss. Every reading carries the status word, and MoxyStatusOkForOxygen() applies the datasheet's rule. See API guide.
  • Blocking or split. MeasureMoxy() waits for the reply; SendMeasure() and TryReadReplyLine() let a loop serve other devices during the measurement. See API guide.
  • Zero-overhead portability. The port is a CRTP class with three methods: no virtual calls, no heap, no RTOS dependency. See Porting.
  • Tested without hardware. Host unit tests run the driver against a model of the sensor's command interface. See Testing and CI.

Where to go next

  • Quickstart

    Wire the sensor, write the port, read oxygen in about 15 lines.

  • Hardware

    Connector pinout, UART settings, timing and power.

  • Architecture

    The three layers and what each one owns.

  • API guide

    Identify, measure, read raw data and handle errors, task by task.

  • Porting

    Implement the UART interface for your MCU.

  • API reference

    Every class and member, generated from the headers.