Sensirion/raspberry-pi-uart-svm4x

C driver to work with the Sensirion's SVM41 sensor modules via UART on Raspberry-Pi

Sensirion Raspberry Pi UART SVM4X Driver

The repository provides a driver for setting up a SVM4X evaluation kit to run on a Raspberry Pi over UART using the SHDLC protocol.

Click here to learn more about the Sensirion SVM4X evaluation kit.

The SVM4x evaluation kit covers evaluation of the SGP40 and SGP41 sensors. This driver supports SVM4x firmware version 3.1.0 and above.

Connect the sensor

Connecting the Sensor over USB

This is the recommended way to connect your sensor. Plug the provided USB cable into your Raspberry Pi and sensor.

Connecting the Sensor over UART Pins

Use the following pins to connect your SVM4X to your Raspberry Pi:

Pin SVM4X	Cable Color	Name	Pin Raspberry Pi	Description	Comments
1	red	VDD	Pin 2	Supply Voltage	3.3 or 5V
2	black	GND	Pin 6	Ground
3	green	RX	Pin 8	UART: Transmission pin for communication
4	yellow	TX	Pin 10	UART: Receiving pin for communication
5	blue	SEL	Pin 4	Interface select	Leave floating or pull to VDD to select UART

Note: Make sure to configure your hardware serial interface on your Raspberry Pi.

Note: Make sure to connect serial pins as cross-over (RX pin of sensor -> TX on Raspberry Pi; TX pin of sensor -> RX pin of Raspberry Pi)

Quick start example

• Install the Raspberry Pi OS on to your Raspberry Pi

• Download the SVM4X driver from Github and extract the .zip on your Raspberry Pi

• Connect the SVM4X sensor as explained in the section above

• Check that the correct serial port is set in the define in sensirion_uart_portdescriptor.h

  • For connection over USB (in case you have other devices connected check the USB number)

    #define SERIAL_0 "/dev/ttyUSB0"

  • For connection over UART Pins

    #define SERIAL_0 "/dev/serial0"

• Compile the driver

  1. Open a terminal

  2. Navigate to the driver directory. E.g. cd ~/raspberry-pi-uart-svm4x

  3. Navigate to the subdirectory example-usage.

  4. Run the make command to compile the driver

     Output:

     rm -f svm4x_uart_example_usage
     cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o svm4x_uart_example_usage svm4x_uart.h svm4x_uart.c sensirion_uart_hal.h sensirion_shdlc.h sensirion_shdlc.c \ 
         sensirion_uart_hal.c sensirion_config.h sensirion_common.h sensirion_common.c svm4x_uart_example_usage.c
     

• Test your connected sensor

  • Run ./svm4x_uart_example_usage in the same directory you used to compile the driver. You should see the measurement values in the console.

Troubleshooting

Building driver failed

If the execution of make in the compilation step 3 fails with something like

 make: command not found

your RaspberryPi likely does not have the build tools installed. Proceed as follows:

$ sudo apt-get update
$ sudo apt-get upgrade
$ sudo apt-get install build-essential

Contributing

Contributions are welcome!

We develop and test this driver using our company internal tools (version control, continuous integration, code review etc.) and automatically synchronize the master branch with GitHub. But this doesn't mean that we don't respond to issues or don't accept pull requests on GitHub. In fact, you're very welcome to open issues or create pull requests :)

This Sensirion library uses clang-format to standardize the formatting of all our .c and .h files. Make sure your contributions are formatted accordingly:

The -i flag will apply the format changes to the files listed.

clang-format -i *.c *.h

Note that differences from this formatting will result in a failed build until they are fixed.

License

See LICENSE.