CO2L Unit

UNIT CO2L is a digital air CO2 concentration detection unit with a single-measurement low-power mode, built-in Sensirion’s SCD41 sensor and power buck circuitry, and I2C communication. The unit is suitable for the measurement of air ambient conditions with a typical accuracy of ± (40 ppm + 5 % reading) for CO2 measurements over a measuring range of 400 ppm – 5000 ppm while measuring ambient temperature and humidity.

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Micropython Example:

# SPDX-FileCopyrightText: 2024 M5Stack Technology CO LTD
#
# SPDX-License-Identifier: MIT

import os, sys, io
import M5
from M5 import *
from hardware import *
from unit import CO2LUnit


title0 = None
label0 = None
label1 = None
label2 = None
label3 = None
i2c0 = None
co2l_0 = None


def setup():
    global title0, label0, label1, label2, label3, i2c0, co2l_0

    M5.begin()
    Widgets.fillScreen(0x222222)
    title0 = Widgets.Title(
        "CO2LUnit CoreS3 Example", 3, 0xFFFFFF, 0x0000FF, Widgets.FONTS.DejaVu18
    )
    label0 = Widgets.Label("label0", 1, 44, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label1 = Widgets.Label("label1", 1, 95, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label2 = Widgets.Label("label2", 1, 146, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label3 = Widgets.Label("label3", 1, 198, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)

    i2c0 = I2C(0, scl=Pin(1), sda=Pin(2), freq=100000)
    co2l_0 = CO2LUnit(i2c0)
    co2l_0.set_start_periodic_measurement()


def loop():
    global title0, label0, label1, label2, label3, i2c0, co2l_0
    if co2l_0.is_data_ready():
        label0.setText(str("Data is ready."))
        label1.setText(str((str("CO2 ppm:") + str((co2l_0.co2)))))
        label2.setText(str((str("Humidity:") + str((co2l_0.humidity)))))
        label3.setText(str((str("Temperature:") + str((co2l_0.temperature)))))
    else:
        label0.setText(str("Data not ready."))


if __name__ == "__main__":
    try:
        setup()
        while True:
            loop()
    except (Exception, KeyboardInterrupt) as e:
        try:
            from utility import print_error_msg

            print_error_msg(e)
        except ImportError:
            print("please update to latest firmware")

UIFLOW2 Example:

co2l_cores3_example.m5f2

class CO2LUnit

Constructors

class CO2LUnit(i2c, address)

Initialize the CO2LUnit with the I2C interface and address.

Parameters:

i2c – I2C interface or PAHUBUnit instance for communication.
address (int) – I2C address of the CO2 sensor, default is 0x62.

UIFLOW2:

Methods

CO2LUnit.available(): Check if the CO2 unit is available on the I2C bus.

CO2LUnit.set_start_periodic_measurement()

Set the sensor into working mode, which takes about 5 seconds per measurement.

UIFLOW2:

CO2LUnit.set_stop_periodic_measurement()

Stop the measurement mode for the sensor.

UIFLOW2:

CO2LUnit.get_sensor_measurement(): Get temperature, humidity, and CO2 concentration from the sensor.

CO2LUnit.is_data_ready()

Check if the data (temperature, humidity, CO2) is ready from the sensor.

UIFLOW2:

CO2LUnit.get_temperature_offset()

Get the temperature offset to be added to the reported measurements.

UIFLOW2:

CO2LUnit.set_temperature_offset(offset)

Set the maximum value of 374°C temperature offset.

Parameters:: offset (int) – The temperature offset to set, default is 0.

UIFLOW2:

CO2LUnit.get_sensor_altitude()

Get the altitude value of the measurement location in meters above sea level.

UIFLOW2:

CO2LUnit.set_sensor_altitude(height)

Set the altitude value of the measurement location in meters above sea level.

Parameters:: height (int) – The altitude in meters to set. Must be between 0 and 65535 meters.

UIFLOW2:

CO2LUnit.set_ambient_pressure(ambient_pressure)

Set the ambient pressure in hPa at any time to adjust CO2 calculations.

Parameters:: ambient_pressure (int) – The ambient pressure in hPa, constrained to the range [0, 65535].

UIFLOW2:

CO2LUnit.set_force_calibration(target_co2)

Force the sensor to recalibrate with a given current CO2 level.

Parameters:: target_co2 (int) – The current CO2 concentration to be used for recalibration.

UIFLOW2:

CO2LUnit.get_calibration_enabled()

Get whether automatic self-calibration (ASC) is enabled or disabled.

UIFLOW2:

CO2LUnit.set_calibration_enabled(enabled)

Enable or disable automatic self-calibration (ASC).

Parameters:: enabled (bool) – Set to True to enable ASC, or False to disable it.

UIFLOW2:

CO2LUnit.set_start_low_periodic_measurement()

Set the sensor into low power working mode, with about 30 seconds per measurement.

UIFLOW2:

CO2LUnit.data_isready(): Check if new data is available from the sensor.

CO2LUnit.save_to_eeprom()

Save temperature offset, altitude offset, and self-calibration enable settings to EEPROM.

UIFLOW2:

CO2LUnit.get_serial_number()

Get a unique serial number for this sensor.

UIFLOW2:

CO2LUnit.set_self_test()

Perform a self-test, which can take up to 10 seconds.

UIFLOW2:

CO2LUnit.set_factory_reset()

Reset all configuration settings stored in the EEPROM and erase the FRC and ASC algorithm history.

UIFLOW2:

CO2LUnit.reinit()

Reinitialize the sensor by reloading user settings from EEPROM.

UIFLOW2:

CO2LUnit.set_single_shot_measurement_all(): Set the sensor to perform a single-shot measurement for CO2, humidity, and temperature.

CO2LUnit.set_single_shot_measurement_ht(): Set the sensor to perform a single-shot measurement for humidity and temperature.

CO2LUnit.set_sleep_mode(): Put the sensor into sleep mode to reduce current consumption.

CO2LUnit.set_wake_up(): Wake up the sensor from sleep mode into idle mode.

CO2LUnit.write_cmd(cmd_wr, value)

Write a command to the sensor.

Parameters:

cmd_wr (int) – The command to write to the sensor.
value (int) – The value to send with the command, if any.

CO2LUnit.read_response(num)

Read the sensor’s response.

Parameters:: num (int) – The number of bytes to read from the sensor.

CO2LUnit.check_crc(buf)

Check the CRC of the received data to ensure it is correct.

Parameters:: buf (bytearray) – The buffer of bytes to check the CRC.

CO2LUnit.crc8(buffer)

Calculate the CRC-8 checksum for a given buffer.

Parameters:: buffer (bytearray) – The buffer of bytes to calculate the CRC for.