Hookup Guide
Schematic
Datasheet (GM-512B)Product Overview
The SparkFun Qwiic Bad Breath Gas Sensor is a compact and solderless solution for detecting concentrations of common volatile organic compounds (VOCs), including hydrogen sulfide (H2S), ammonia (NH3), acetone (C3H6O), and alcohol (CH3CH2OH), in indoor environments. Utilizing the Winsen GM-512B MEMS sensor, it detects concentrations between 0.5 and 50 parts per million (ppm), routing the sensor's analog voltage fluctuations into an onboard 10-bit analog-to-digital converter (ADC) that delivers a clean digital signal directly over I2C.
Qualitative Measurement & Calibration
While the GM-512B measures hydrogen sulfide and other breath-emitted gas concentrations, it returns only qualitative data; the data does not represent a specific concentration in ppm.
- Built-in ADC: The onboard 10-bit analog-to-digital converter takes the sensor's raw analog voltage output (with a sensitive material resistance of 1KΩ to 30KΩ) and feeds the converted data to your microcontroller over I2C (default address 0x56).
- Sensor Calibration: Because the baseline values are uncalibrated and may cross over with other gases, you'll need to calibrate the output against known concentrations of hydrogen sulfide, ammonia, acetone, and alcohol to extract useful ppm data.
- Operation Efficiency: Includes an onboard LDO power regulator configured to power the internal sensor heater with an 80Ω ±20Ω room-temperature resistance that consumes less than 50mW of power.
This breakout features a pair of Qwiic connectors for a completely solderless setup and works directly with the SparkFun GM-XX2B Arduino Library. For users who prefer a traditional breadboard circuit or need direct access to the analog signal, standard 0.1-inch-spaced plated through-hole (PTH) pins break out the 3.3V power, I2C lines, ADC Alert signal, and the sensor's raw VOUT signal.
