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https://github.com/sensirion/raspberry-pi-i2c-sen5x

C driver to work with Sensirion's SEN5x environmental sensor modules via I2C
https://github.com/sensirion/raspberry-pi-i2c-sen5x

all-in-one driver environmental evaluation-kit i2c module nox particulate-matter raspberry-pi relative-humidity sek sen54 sen55 sen5x sensirion sensor temperature voc

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C driver to work with Sensirion's SEN5x environmental sensor modules via I2C

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README

        

# Sensirion Raspberry Pi I2C SEN5x Driver

This document explains how to set up the Sen5x sensor to run on a Raspberry Pi using the provided code.

## Supported sensors

- SEN50 (only particulate matter signals available)
- SEN54 (no NOx signal available)
- SEN55 (full feature set)

## 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 SEN5x:

*SEN5x* | *Raspberry Pi* | *Jumper Wire* |
:------: | :-------------------------: | :---------------: |
VCC | Pin 2 (5V) | Red |
GND | Pin 6 | Black |
SDA | Pin 3 | Green |
SCL | Pin 5 | Yellow |
SEL | Pin 9 (GND for I2C) | Blue |

| *Pin* | *Name* | *Description* | *Comments* |
|-------|--------|---------------------------------|----------------------------------|
| 1 | VCC | Supply Voltage | 5V ±10%
| 2 | GND | Ground |
| 3 | SDA | I2C: Serial data input / output | TTL 5V and LVTTL 3.3V compatible
| 4 | SCL | I2C: Serial clock input | TTL 5V and LVTTL 3.3V compatible
| 5 | SEL | Interface select | Pull to GND to select I2C
| 6 | NC | Do not connect |

### Raspberry Pi

- [Install the Raspberry Pi OS on to your Raspberry Pi](https://projects.raspberrypi.org/en/projects/raspberry-pi-setting-up)
- [Enable the I2C interface in the raspi-config](https://www.raspberrypi.org/documentation/configuration/raspi-config.md)
- Download the driver for the [Sensirion Github Page](https://github.com/Sensirion/raspberry-pi-i2c-sen5x) and extract the `.zip` on your Raspberry Pi
- Compile the driver
1. Open a [terminal](https://www.raspberrypi.org/documentation/usage/terminal/?)
2. Navigate to the driver directory. E.g. `cd ~/raspberry-pi-i2c-sen5x`
3. Run the `make` command to compile the driver

Output:
```
rm -f sen5x_i2c_example_usage
cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o sen5x_i2c_example_usage sen5x_i2c.h sen5x_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 sen5x_i2c_example_usage.c
```
- Test your connected sensor
- Run `./sen5x_i2c_example_usage` in the same directory you used to
compile the driver.

Output:
```
Serial number: 213100019
Product name:
Firmware: 1.0, Hardware: 4.0
Mass concentration pm1p0: 0.0 µg/m³
Mass concentration pm2p5: 0.0 µg/m³
Mass concentration pm4p0: 0.0 µg/m³
Mass concentration pm10p0: 0.0 µg/m³
Ambient humidity: 39.6 %RH
Ambient temperature: 28.0 °C
Voc index: 0.0
Nox index: 0.0
Mass concentration pm1p0: 0.0 µg/m³
Mass concentration pm2p5: 0.0 µg/m³
Mass concentration pm4p0: 0.0 µg/m³
Mass concentration pm10p0: 0.0 µg/m³
Ambient humidity: 39.2 %RH
Ambient temperature: 30.1 °C
Voc index: 0.0
Nox index: 0.0
...
```

- Wait a few minutes until Voc/NOx index values are stable.

## Troubleshooting

### Building driver failed

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

> -bash: 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
```

### 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 ./sen5x_i2c_example_usage`), it's
typically due to wrong permission settings. See the next chapter how to solve this.

### Missing I2C permissions

If your user is missing access to the I2C interface you should first verfiy
the user belongs to the `i2c` group.

```
$ groups
users input some other groups etc
```
If `i2c` is missing in the list add the user and restart the Raspberry Pi.

```
$ sudo adduser ${USER} i2c
Adding user `pi' to group `i2c' ...
Adding user pi to group i2c
Done.
$ sudo reboot
```

If that did not help you can make globally accessible hardware interfaces
with a udev rule. Only do this if everything else failed and you are
reasonably confident you are the only one having access to your Pi.

Go into the `/etc/udev/rules.d` folder and add a new file named
`local.rules`.
```
$ cd /etc/udev/rules.d/
$ sudo touch local.rules
```
Then add a single line `ACTION=="add", KERNEL=="i2c-[0-1]*", MODE="0666"`
to the file with your favorite editor.
```
$ sudo vi local.rules
```