CCS811 MicroPython for Raspberry Pi PICO

ccs811.py

import time
from machine import I2C, Pin

_ADDR = 0x5B


class CCS811:
    def __init__(self, i2c: I2C):
        self._i2c = i2c

    def setup(self):
        print("setup CCS811")
        self.multi_write_register(0xFF, b"\x11\xE5\x72\x8A")  # RESET
        time.sleep_ms(100)

        self.check_for_status_error()
        self.app_valid()

        self._i2c.writeto_mem(_ADDR, 0xF4, b"")  # APP_START
        time.sleep_ms(100)
        self.set_driver_mode(1)
        time.sleep_ms(100)

    def data_available(self) -> bool:
        v = self._i2c.readfrom_mem(_ADDR, 0x00, 1)
        if v[0] & 1:
            e = self.read_register(0xE0)
            print("error register", hex(e[0]))
        return (v[0] & 1 << 3) > 0

    def check_for_status_error(self) -> bool:
        v = self.read_register(0x00)
        return (v[0] & 1 << 0) > 0

    def app_valid(self):
        v = self.read_register(0x00)
        return (v[0] & 1 << 4) > 0

    def set_driver_mode(self, mode: int):
        v = self.read_register(0x01)  # MEAS_MODE
        v = v[0]
        v &= ~(0b00000111 << 4)  # Clear DRIVE_MODE bits
        v |= mode << 4  # Mask in mode
        self.write_register(0x01, v)

    def read_algorithm_results(self):
        v = self.multi_read_register(0x02, 4)  # ALG_RESULT_DATA
        co2 = v[0] << 8 | v[1]
        t_voc = v[2] << 8 | v[3]
        return co2, t_voc

    def write_register(self, offset: int, value: int):
        return self._i2c.writeto_mem(_ADDR, offset, bytes([value]))

    def read_register(self, offset: int):
        return self._i2c.readfrom_mem(_ADDR, offset, 1)

    def multi_write_register(self, offset: int, data: bytes):
        self._i2c.writeto_mem(_ADDR, offset, data)

    def multi_read_register(self, offset: int, length: int):
        return self._i2c.readfrom_mem(_ADDR, offset, length)

    def status(self):
        b = self._i2c.readfrom(_ADDR, 1)
        return b[0]


def main():
    i2c = I2C(0, sda=Pin(8), scl=Pin(9))
    c = CCS811(i2c)
    c.setup()
    while True:
        if c.data_available():
            r = c.read_algorithm_results()
            print("CO2={},tVOC={}".format(r[0], r[1]))
        time.sleep(1)