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Temp/Pres/Hum/VOC Wireling Python Tutorial

This Wireling lets you measure Temperature, Pressure, Humidity, and Volatile Organic Compounds (VOCs) via the BME680. This Wireling sensor is an upgrade from the Pressure & Humidity Wireling that uses the BME680 to measure relative humidity, barometric pressure, ambient temperature and gas (VOC).

Technical Details

Bosch BME680 Sensor Specs

  • Digital interface I²C (up to 3.4 MHz) and SPI (3 and 4 wire, up to 10 MHz)
  • Operating range -40 - +85°C, 0-100 % r.H., 300-1100 hPa
  • Humidity, Pressure, Gas sensor can be independently enabled / disabled
  • RoHS compliant, halogen-free, MSL1

Pressure Sensor

  • RMS Noise 0.12 Pa, equiv. to 1.7 cm
  • Offset temperature coefficient ±1.3 Pa/K, equiv. to ±10.9 cm at 1 °C temperature change

Humidity Sensor

  • Response time 8 s
  • Accuracy tolerance ±3 % relative humidity
  • Hysteresis ±1.5% relative humidity

Gas Sensor

  • Response time < 1s (for new sensors)
  • Power consumption < 0.1mA in ultra-low power mode
  • Output data processing: direct index for air quality (IAQ) output

    TinyDuino Power Requirements

    • Voltage: 3.0V - 5.5V 
    • Current:
      • 2.1 µA @ 1 Hz humidity and temperature
      • 3.1 µA @ 1 Hz pressure and temperature
      • 3.7 µA @ 1 Hz humidity, pressure, and temperature
      • 0.15 µA in sleep mode

    Materials

    Hardware

    Required Software

    • Python 3 (Python 2 is not supported!)
    • All Python packages mentioned in the Pi Hat setup tutorial (tinycircuits-wireling, adafruit-circuitpython-bme680, adafruit-circuitpython-ads1x15, and adafruit-circuitpython-busdevice)
    • BME680 Python Example

    Hardware Assembly

    Plug your Wireling into the port you plan on using! The default in the included program is port 0.

    If you want to use a different port, you just need to change the port value in the program mentioned later.


    Programming

    Install the necessary Python package:

    pip3 install adafruit-circuitpython-bme680
    

    Then you can download (above under Software) the Ambient Light Sensor Wireling example:

    BME680_example.py
    # TinyCircuits Temp/Press/Hum/VOC BME680 Wireling Example
    # Prints values of temperature, VOC, humidity, pressure,
    # and altitude read by the sensor every 2 seconds.
    # Initialized: 01-21-2020
    # Last Updated: 01-21-2020
    
    from busio import I2C
    import adafruit_bme680
    import time
    import board
    import tinycircuits_wireling
    
    # Initialize and enable power to Wireling Pi Hat
    wireling = tinycircuits_wireling.Wireling()
    
    # Toggle this variable to use the Wireling on a different port (0-3)
    port = 0
    wireling.selectPort(port)
    
    # Create library object using our Bus I2C port
    i2c = I2C(board.SCL, board.SDA)
    bme680 = adafruit_bme680.Adafruit_BME680_I2C(i2c, 0x76) # our Wireling has an address of 0x76
    
    # change this to match the location's pressure (hPa) at sea level
    bme680.sea_level_pressure = 1013.25
    
    while True:
        print("\nTemperature: %0.1f C" % bme680.temperature)
        print("Gas: %d ohm" % bme680.gas)
        print("Humidity: %0.1f %%" % bme680.humidity)
        print("Pressure: %0.3f hPa" % bme680.pressure)
        print("Altitude = %0.2f meters" % bme680.altitude)
    
        time.sleep(2)
    

    The program by default is written to work with Port 0 on the Wireling Pi Hat.


    Run Program

    Navigate in the terminal to the directory where you downloaded or saved the python example and run:

    python3 BME680_example.py
    

    Be sure pigpiod is running before you attempt to run the python program. This is done by running the following command:

    sudo pigpiod
    

    The program will print the temperature, VOC, humidity, pressure, and altitude readings from the sensor every 2 seconds.


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    Downloads