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Sensirion Raspberry Pi I2C SGP41 Driver

This document explains how to set up the SGP41 sensor to run on a Raspberry Pi using the provided code.

<center><img src="images/SGP41.png" width="300px"></center>

Click here to learn more about the SGP41 Sensor.

Setup Guide

Connecting the Sensor

Your sensor has the four different connectors: VCC, GND, SDA, SCL. Use the following pins to connect your SGP41:

Raspberry Pi

• Install the Raspberry Pi OS on to your Raspberry Pi
• Enable the I2C interface in the raspi-config
• Download the driver for the Sensirion Github Page and extract the .zip on your Raspberry Pi
• Compile the driver

  1. Open a terminal

  2. Navigate to the driver directory. E.g. cd ~/raspberry-pi-i2c-sgp41

  3. Run the make command to compile the driver

     Output:

     rm -f sgp41_i2c_example_usage
     cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o sgp41_i2c_example_usage  sgp41_i2c.h sgp41_i2c.c sensirion_i2c_hal.h sensirion_i2c.h sensirion_i2c.c \
         sensirion_i2c_hal.c sensirion_config.h sensirion_common.h sensirion_common.c sgp41_i2c_example_usage.c
     

• Test your connected sensor

  • Run ./sgp41_i2c_example_usage in the same directory you used to compile the driver.

    Output:

    SRAW VOC: 25720
    SRAW NOx: conditioning
    SRAW VOC: 25846
    SRAW NOx: conditioning
    ...
    SRAW VOC: 25951
    SRAW NOx: 15656
    SRAW VOC: 26153
    SRAW NOx: 15612
    SRAW VOC: 26278
    SRAW NOx: 15553
    ...
    

Conditioning

After each restart of the sensor or when the hotplates have been switched off, the conditioning command must be called from idle mode. The conditioning heats the hotplate of the NOx pixel to a different temperature compared to the measurement mode enabling a faster switch-on thereafter.

It is recommended to execute the conditioning for 10s, but 10s must not be exceeded to avoid damage to the sensing material.

Troubleshooting

Initialization failed

• Ensure that you connected the sensor correctly: All cables are fully plugged in and connected to the correct pin.
• Ensure that I2C is enabled on the Raspberry Pi. For this redo the steps on "Enable the I2C interface in the raspi-config" in the guide above.
• Ensure that your user account has read and write access to the I2C device. If it only works with user root (sudo ./sgp41_i2c_example_usage), it's typically due to wrong permission settings.