Introduction

Driver in MicroPython for CC811: Ultra-Low Power Digital Gas Sensor for Monitoring Indoor Air Quality The driver covers 100% of the sensor's application register:

• Get status register and raise ValueError when the status register reports an error.
• Give measurement mode and conditions register.
• Get ppm estimate of the equivalent CO₂ (eCO₂) level and ppb estimate of the total VOC (eTVOC) level.
• Get raw ADC data values for resistance with voltage (V) and current (μA) source used.
• Give temperature and humidity data to enable compensation.
• Give Thresholds for operation when interrupts are only generated when eCO₂ ppm crosses a threshold.
• Get/Give the baseline value.
• Get the hardware ID.
• Get the hardware version.
• Get the firmware boot version.
• Get the firmware application version.
• Reset the device and return to boot mode.
• Update the application with binary file

Dependencies

This driver has no dependency

Install

Copy the python files in your project folder.

Usage Example

The driver is split into several classes, because the methods and attributes available can be very different depending on the mode and operation. To simplify use of the driver, a factory class (CCS811Factory) will select the right class to use for you, depending on the options you choose

Basic use in mode 1, 2 or 3 on wemos D1 mini:

.. code-block:: micropython

import time
from machine import Pin, I2C
from ccs811factory import CCS811Factory

ccs811 = CCS811Factory(I2C(scl=Pin(5), sda=Pin(4)))

while True:
    if ccs811.data_is_ready:
        #ccs811.temperature = another_sensor.get_temp()
        #ccs811.humidity = another_sensor.get_hum()
        
        print(ccs811.eco2, "ppm and ", ccs811.etvoc, "ppb")
    time.sleep(1)

Use in mode 1, 2 or 3 with interrupt and thresholds on wemos D1 mini:

.. code-block:: micropython

import time
from machine import Pin, I2C
from ccs811factory import CCS811Factory
from ccs811 import CCS_MODE_3

i2c = I2C(scl=Pin(5), sda=Pin(4))
ccs811 = CCS811Factory(i2c, mode=CCS_MODE_3, with_int=True, with_thresh=True)
#Change default values:
ccs811.low_threshold = 800
ccs811.high_threshold = 1000

def data_is_ready(pin):
    print("warning: eCO2 ppm crosses a threshold!")
    print(ccs811.eco2, "ppm and ", ccs811.etvoc, "ppb")
pin_int = Pin(0, Pin.IN, Pin.PULL_UP)
pin_int.irq(data_is_ready, Pin.IRQ_FALLING)

# Pin.IRQ_LOW_LEVEL is not available on wemos D1 mini,
# so a first pass must be made if a value was already available
# before the interrupt handler was set up.
if not pin_int.value():
    data_is_ready(pin_int)

while True:
    #ccs811.temperature = another_sensor.get_temp()
    #ccs811.humidity = another_sensor.get_hum()
    
    # Mode 3 – Low power pulse heating mode IAQ measurement every 60s
    time.sleep(60)

Use in mode 4 with wemos D1 mini:

.. code-block:: micropython

import time
from machine import Pin, I2C
from ccs811factory import CCS811Factory
from ccs811 import CCS_MODE_4

i2c = I2C(scl=Pin(5), sda=Pin(4))
ccs811 = CCS811Factory(i2c, mode=CCS_MODE_4)

while True:
    if ccs811.data_is_ready:
        #ccs811.temperature = another_sensor.get_temp()
        #ccs811.humidity = another_sensor.get_hum()
        
        print(ccs811.voltage,"v and ",ccs811.current,"μA")
    time.sleep(0.25)

Documentation

Read the code.

Contributing

Contributions are welcome!