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 unmatched robustness against contaminating gases present in real-world applications enabling 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 bevelled edge connector to their respective key on the M.2 connector, then secure them to the mainboard 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.
Typ. ~3.7V to 4.2V via Main Board's LiPo battery Connector
IO 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.
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