The SparkFun MicroMod Environmental Function Board adds additional sensing options to the MicroMod Processor Boards. This Function Board includes three sensors to monitor air quality (SGP40), humidity & temperature (SHTC3), and CO₂ concentrations (STC31) in your indoor environment. To make it even easier to use, all communication is over the MicroMod's I²C bus!

• The SGP40 measures the quality of the air in your room or house. The SGP40 uses a metal oxide (MOx) sensor with a temperature controlled micro hotplate and provides a humidity-compensated volatile organic compound (VOC) based indoor air quality signal. Both the sensing element and VOC Algorithm feature an unmatched robustness against contaminating gases present in real world applications enabling a unique long term stability as well as low drift and device to device variation.

• The SHTC3 is a highly accurate digital humidity and temperature sensor. The SHTC3 uses a capacitive humidity sensor with a relative humidity measurement range of 0 to 100% RH and bandgap temperature sensor with a temperature measurement range of -40°C to 125°C. The SHTC3 builds on the success of their SHTC1 sensor with higher accuracy (±2% RH, ±0.2°C) than its predecessor, enabling greater flexibility.

• The STC31 measures CO₂ concentrations based on thermal conductivity and has two CO₂ measurement ranges: 0 to 25 vol%; and 0 to 100 vol%. The measurement repeatability is 0.2 vol%, with a stability of 0.025 vol% / °C. The measurement accuracy depends on the measurement range: 0.5 vol% + 3% measured value; 1 vol% + 3% measured value. Using measurements from the SHTC3, the STC31 is able to provide humidity-compensated measurements together with improved temperature compensation. The STC31 can compensate for atmospheric pressure too - which is handy if, like us, you’re up in the mountains!

The outstanding performance of these three sensors is based on Sensirion’s patented CMOSens^® technology, which combines the sensor element, signal processing, and digital calibration on a small CMOS chip. The well-proven CMOS technology is perfectly suited for high-quality mass production and is the ideal choice for demanding and cost-sensitive OEM applications.

Utilizing our handy M.2 MicroMod connector, no soldering is required to connect it to your system. Simply match up the key on your processor and function board's beveled edge connector to their respective key on the M.2 connector, then secure them to the main board with screws. The MicroMod Environmental Function Board can then be read via the I²C port. The board is equipped with the AP2112 3.3V voltage regulator, I²C pull-up resistors, power LED, jumper to disable the LED, and jumpers for alternative STC31 addresses.

Note: A MicroMod Processor and Main Board are not included with this MicroMod Environmental Function Board. These boards will need to be purchased separately.

MicroMod is a modular interface ecosystem that connects a microcontroller “processor board” to various “carrier board” peripherals. Utilizing the M.2 standard, the MicroMod standard is designed to easily swap out processors and function boards on the fly. Pair a specialized carrier board for the project you need with your choice of compatible processor!

• Input voltage range
  • 2.5V to 6.0V
    • Typ. 5V via Main Board's USB connector
    • Typ. ~3.7V to 4.2V via Main Board's LiPo battery Connector
• I/O voltage
  • 3.3V
• AP2112 3.3V voltage regulator (rated 600mA)
• Power LED
• I²C pull-up resistors
• Sensirion SGP40 Air Quality Sensor
  • Uses I²C interface
    • Address: 0x59 (default)
  • Operating voltage range
    • 1.7V to 3.6V (Typ. 3.3V)
  • Operating temperature range
    • -20°C to +55°C
  • Typical current consumption
    • 2.6mA during continuous operation (at 3.3V)
    • 34µA when idle (heater off)
  • Output signal
    • Digital raw value (SRAW): 0 - 65535 ticks
    • Digital processed value (VOC Index): 0 - 500 VOC index points
  • Switch-on behavior
    • Time until reliably detecting VOC events: <60s
    • Time until specifications are met: <1h
  • Recommended sampling interval
    • VOC Index: 1s
    • SRAW: 0.5s - 10s (Typ. 1s)
• Sensirion SHTC3 Humidity and Temperature Sensor
  • Uses I²C interface
    • Address: 0x70 (default, non-configurable)
  • Operating voltage range
    • 1.62V - 3.6V (Typ. 3.3V)
  • Operating temperature range
    • -40°C to +125 °C
  • Relative Humidity
    • Measurement range: 0% to 100%
    • Typical accuracy: ±2 %RH
    • Resolution: 0.01 %RH
  • Temperature
    • Measurement range: -40°C to +125 °C
    • Typical accuracy: ±0.2 °C
    • Resolution: 0.01 °C
  • Typical current consumption (varies based on mode)
    • 4.9µA to 430µA (Normal Mode)
    • 0.5µA to 270µA (Low Power Mode)
  • Allows the STC31 to compensate for humidity and temperature
• Sensirion STC31 CO₂ Sensor
  • Uses I²C interface
    • Addresses: 0x29 (default), 0x2A, 0x2B, 0x2C
  • Operating voltage range
    • 2.7V to 5.5V (Typ. 3.3V)
  • Operating temperature range
    • -20 °C to +85 °C
  • Calibrated for CO₂ in N₂ and CO₂ in air
  • Measurement ranges
    • 0 to 25 vol% in N₂
    • 0 to 100 vol% in air
  • Accuracy
    • 0.5 vol% + 3% measured value in N₂
    • 1 vol% + 3% measured value in air
  • Concentration and temperature resolution: 16-bit
  • Repeatability: 0.2 vol%
  • Temperature stability: 0.025 vol% / °C
  • Start-up time: 14 ms
  • Thermal conductivity sensor provides calibrated gas concentration and temperature output
• Jumpers
  • PWR LED
  • I²C pull-up resistors
  • STC31 address selection

Note: The I²C addresses that are reserved for each sensor is 0x59 (SGP40), 0x70 (SHTC3), 0x29 (STC31). A multiplexer/Mux is required to communicate to multiple SHTC3 sensors on a single bus. The SHTC3 uses the same address as the Qwiic Mux (0x70). For advanced users that are using multiple SHTC3's with the Qwiic Mux, you will need to adjust the Qwiic Mux's default address.

Hardware Documentation:

• Schematic
• Eagle Files
• Board Dimensions
• Hookup Guide
• SGP40
  • SGP40 Datasheet
  • VOC Index for Experts
  • SGP40 Design In Guide
  • SGP40 Quick Testing Guide
• SHTC3
  • SHTC3 Datasheet
• STC3X
  • STC31 Datasheet
  • STC Field Calibration Guide
  • STC Design-In Guide
• Arduino Libraries
  • SGP40
  • SHTC3
  • STC3X
• GitHub Hardware Repo

MicroMod Documentation:

• Getting Started with MicroMod
• Designing with MicroMod
• MicroMod Info Page
• MicroMod Forums