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Environmental Sensor FeatherWing

Actinius I/O Serial Programmer


The Actinius FeatherWing is an environmental sensing board that can measure and detect light intensity, temperature, humidity, air pressure and gas mixtures. All of the on-board sensors are accessed through the I2C-bus, which is available through the pin headers and a Grove connector. Note that the board has 4.7 kOhms pull-up resistors on the I2C lines so external pull-ups are not necessary. The FeatherWing also has datalogging capabilities through a micro SD-card connector and the SPI.

Sensors and features

  • BME688 Gas sensor
  • Second BME688 Gas sensor (optional)
  • OPT3002 Ambient light sensor
  • SI7060 Temperature sensor
  • Micro SD-card connector
  • Grove connector for I2C
  • 4.7 kOhms pull-ups on the I2C-bus

BME688 Gas sensors

The BME688 sensor on the FeatherWing can measure several environmental parameters and cointains an AI-core that can be trained to detect certain gas compositions. The BME688 can measure the following:

  • Temperature
  • Humidity
  • Pressure
  • Gases:
    • Gas resistance
    • Volatile Organic Compounds (VOCs)
    • Breath VOCs (b-VOCs)
    • Volatile Sulfur Compounds (VSCs)
    • Index for Air Quality (IAQ)
    • Carbon dioxide - CO2
    • Carbon monoxide - CO
    • Hydrogen Sulfide - H2S
    • Ethanol alcohol - EtOH
    • Various gas mixtures

More information about the capabilities of the BME688 sensor can be found in the BME688 datasheet.

Each FeatherWing comes with one BME688, and an optional second BME688 which can be used to detect more gas mixtures. The I2C address of the primary BME688_1 is 0x76. The second optional sensor BME688_2 has an I2C address of 0x77.

Bosch provides the BME AI-Studio tool which allows developers to train the BME688 to detect certain gas mixtures and smells. More information can be found on the BME688 software page. An example of a use case that is given by Bosch is the detection of coffee beans. Other usecases could be: fire detection, spoiled food detection or bad breath detection.

Temperature sensor specification:

Operating temperature range-402585C
Supply current (1 Hz forced mode)1.0uA
Absolute accuracy at 25 C0.5C
Absolute accurace at 0-65 C1.0C
Output resolution0.01C
RMS noise0.005C

Humidity sensor specification:

Operating range-402585C
0100% RH
Full accuracy range065C
1090% RH
Supply current (1 Hz forced mode)1.11.8uA
Absolute accuracy at 25 C3.0% RH
Absolute accurace at 0-65 C1.0C
Output resolution0.008C
RMS noise0.01% RH
Long term stability0.5% RH / year

Pressure sensor specification:

Operating temperature range-402585C
Full accuracy temperature range065C
Operating pressure range (full accuracy)3001100hPa
Supply current (1 Hz forced mode)1.12.2uA
Absolute accuracy pressure (300-1100 hPa)0.6hPa
Relative accuracy pressure (700-1100 hPa)0.12hPa
Output resolution0.18Pa
RMS noise1.4Pa
Long term stability1.0Pa / year

Gas sensor specification:

Operating range-402585C
1095% RH
Supply current during heater operation91213mA
Peak supply current151718mA
Average supply current (ultra-low power mode)0.09mA
Average supply current (low power mode)0.9mA
Average supply current (continuous mode)12mA
Resolution of gas sensor resistance0.050.080.11%
RMS noise in gas sensor resistance1.5%
IAQ resolution1
IAQ range0500

BME688 schematics:

BME688 schematics

BME688 schematics

OPT3002 Ambient light sensor

The OPT3002 is a ambient light-to-digital sensor that can measure light intensity in the 300 nm to 1000 nm range. The sensor is pre-callibrated and its values are compensated for dark-current effects and temperature variations. Furthermore, the sensor features a automatic range selection mode. This mode automatically selects the optical range setting for the detected lighting condition. This eliminates the requirement of programming measurement and reajustments cycles of the full-scale range. The OPT3002 also reduces noise from 50 Hz and 60 Hz light sources by integrating its results over either 100 ms or 800 ms.

The sensor comes with a INT interrupt pin that is accessible through pin A4 on the FeatherWing. The interrupt events are controlled by the high-limit and low-limit registers of the OPT3002. See the OPT3002 datasheet for more information on the interrupt capabilities of the sensor.

The I2C address of the OPT3002 is 0x44.

OPT3002 specification

Operating temperature range-402585C
Optical range3001000nm
Peak irradiance spectral responsivity505nm
Resolution (LSB) at 505 nm0.008196lux
Full-scale illuminance at 505 nm72671.2lux
Relative accuracy between gain ranges0.2%
Half-power angle (50% of full-power reading)60Degrees
Quiescent current in active mode1.83.7uA
Quiescent current in shutdown mode0.3600.47uA

OPT3002 schematics:

OPT3002 schematics

OPT3002 schematics

SI7060 Temperature sensor

The SI7060 is a simple low-power temperature sensor. It can be used to increase the accuracy of the BME688 temperature sensor by comparing it's measurement results with those of the SI7060.

The SI7060 comes in 4 variants with different I2C addresses. The sensor FeatherWing comes with the SI7060-B-02-IV(R) which has the following I2C address: 0x32. More information about the sensor can be found in the SI7060 datasheet.

SI7060 specification:

Operating temperature range-4025125C
Temperature measurement accuracy (0 to 70 C)0.51.0C
Temperature measurement accuracy (-40 to 125 C)2.0C
RMS noise0.05C
Current consumption (sleep timer + 200 ms sample rate)0.51.5uA
Current consumption (sleep mode at 25 C)0.05uA
Current consumption (sleep mode at 125 C)1.0uA
Current consumption (During conversion / active mode)600800uA
Conversion time143160us
Sleep time160200240us

SI7060 schematics:

The SI7060 has an ALERT pin that can be programmed to trigger when a certain temperature is measured by the sensor. The ALERT signal is accessible through pin D6 on the FeatherWing after soldering the open jumper connection on the board (marked with ALERT).

OPT3002 schematics

OPT3002 schematics

Micro SD-card connector

The Micro SD-card connector can be used for datalogging and saving the values measured by the sensors on the board. The SD-card can be accessed through the SPI-bus. The pins of the SPI bus are labeled on the FeatherWing board. The chip select pin of the SD-card is connected to pin A5 on the FeatherWing.

Grove connector

The environmental FeatherWing board provides an I2C grove connector to easily connect to a microcontroller or other sensor without having to solder wires. The Grove connector has the following pinout:

Grove connector pinout

Grove connector pinout