Sensirion Raspberry Pi I2C SVM40 Driver

This document explains how to set up the SEK-SVM40 sensor module to run on a Raspberry Pi using the provided code.

Setup Guide

Connecting the Sensor

Your sensor has the five different connectors: VCC, GND, SDA, SCL, SEL (the sixth connector will not be used for now). Use the following pins to connect your SVM40:

SVM40	Raspberry Pi	Jumper Wire
VCC	Pin 1 or 2 (3.3V or 5V)	Red
GND	Pin 6	Black
SDA	Pin 3	Green
SCL	Pin 5	Yellow
SEL	Pin 9 (GND for I2C)	Blue

If you don't have a suitable cable at hand, please find the SEK-SVM40 pinout listed below, or in the technical documentation:

Pin	Cable Color	Name	Description	Comments
1	Red	VDD	Supply Voltage	3.3 or 5.0 V
2	Black	Ground
3	Green	RX	UART: Receiving pin for communication
		SDA	I2C: Serial data, bidirectional
4	Yellow	TX	UART: Transmission pin for communication
		SCL	I2C: Serial clock
5	Blue	SEL	Interface select	Leave floating or pull to VDD to select UART
				Pull to GND to select I2C
6	Purple	NC	Do not connect

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-svm40

  3. Run the make command to compile the driver

     Output:

     rm -f svm40_i2c_example_usage
     cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o svm40_i2c_example_usage  svm40_i2c.h svm40_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 svm40_i2c_example_usage.c
     

• Test your connected sensor

  • Run ./svm40_i2c_example_usage in the same directory you used to compile the driver.

    Output:

    Serial number: 0FDBE89C00000237AE113220
    Firmware: 2.2 Debug: 0
    Hardware: 2.0
    Protocol: 1.0
    Temperature Offset: 0.00 °C
    Voc index: 0.0
    Humidity: 39.07 %RH
    Temperature: 24.82 °C
    Voc index: 0.0
    Humidity: 39.02 %RH
    Temperature: 24.82 °C
    ...
    

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 ./svm40_i2c_example_usage), it's typically due to wrong permission settings.