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Sensirion Raspberry Pi UART SEN44 Driver

This document explains how to set up the SEN44 sensor module to run on a Raspberry Pi using the provided code.

Setup Guide

Connecting the Sensor

Plug the provided USB cable into your Raspberry Pi.

If you don't have a suitable cable at hand, please find the SEN44 pinout listed below:

Pin	Name	Description	Comments
1	VDD	Supply Voltage	5V ±10%
2	GND	Ground
3	RX	UART: Receiving pin for communication	TTL 5V and LVTTL 3.3V compatible
	SDA	I2C: Serial data input / output	TTL 5V and LVTTL 3.3V compatible
4	TX	UART: Transmission pin for communication	TTL 5V and LVTTL 3.3V compatible
	SCL	I2C: Serial clock input	TTL 5V and LVTTL 3.3V compatible
5	SEL	Interface select	Leave floating or pull to VDD to select UART
			Pull to GND to select I2C
6	NC	Do not connect

Raspberry Pi

Install the Raspberry Pi OS on to your Raspberry Pi
Download the driver from the Sensirion GitHub Page and extract the .zip on your Raspberry Pi

Compile the driver

Open a terminal
Navigate to the driver directory. E.g. cd ~/raspberry-pi-uart-sen44

Run the make command to compile the driver

Output:

rm -f sen44_uart_example_usage
cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o sen44_uart_example_usage sen44_uart.h sen44_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 sen44_uart_example_usage.c

Test your connected sensor

Run ./sen44_uart_example_usage in the same directory you used to compile the driver.

Output:

Serial number: C081C2651224B6FE
Firmware: 0.4, Hardware: 6.0, protocol: 2.0
Mass concentration pm1p0: 1
Mass concentration pm2p5: 5
Mass concentration pm4p0: 9
Mass concentration pm10p0: 11
Voc index: 0.0
Ambient humidity: 40.81%RH
Ambient temperature: 24.58°C
Mass concentration pm1p0: 1
Mass concentration pm2p5: 3
Mass concentration pm4p0: 4
Mass concentration pm10p0: 4
Voc index: 0.0
Ambient humidity: 40.81%RH
Ambient temperature: 24.58°C
...