• Narcisa Ana Maria Vasile's avatar
    iio: chemical: ccs811: Add support for AMS CCS811 VOC sensor · a94c24a7
    Narcisa Ana Maria Vasile authored
    
    
    Add support for CCS811 VOC sensor. This patch adds support
    for reading current and voltage across the sensor and TVOC
    and equivalent CO2 values.
    
    Scale and offset values have been computed according to datasheet:
        - For current: raw value is in microamps
            => 0.001 scale to convert to milliamps
        - For voltage: 1.65V = 1023, therefore 1650mV = 1023
            => 1650.0/1023 = 1.612903 scale to convert to millivolts
        - For eCO2: raw value range is from 400ppm to 8192ppm.
            => (val - 400) * (100 - 0) / (8192 - 400) + 0 =
               (val - 400) * 0.01283367 => offset: -400, scale = 0.012834
               to get a percentage value
        -For TVOC: raw value range is from 0ppb to 1187ppb.
            => (val - 0) * 100 / (1187 - 0) + 0 = val * 0.0842459 =>
                scale = 0.084246 for getting a percentage value
    
    Cc: Daniel Baluta <daniel.baluta@gmail.com>
    Cc: Alison Schofield <amsfield22@gmail.com>
    Signed-off-by: default avatarNarcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>
    Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
    a94c24a7
ccs811.c 8.08 KB