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https://github.com/sensirion/embedded-i2c-sen5x

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

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

Last synced: 4 days ago
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Generic embedded C driver to work with Sensirion's SEN5x environmental sensor modules via I2C

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README 

        
# Sensirion Embedded I2C SEN5x Driver



This is a generic embedded driver for the Sensirion SEN5x sensor modules. It enables developers to communicate with the

SEN54/SEN55 sensor module on different hardware platforms by only adapting the I2C communication related source files.






## Supported sensors



- SEN50 (only particulate matter signals available)

- SEN54 (no NOx signal available)

- SEN55 (full feature set)



# Getting started



## Connecting the Sensor



Your sensor has the five different connectors: VCC, GND, SDA, SCL, SEL (the sixth connector will not be used for now).






| *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 enable I2C interface

| 6     | NC     | Do not connect                  |



## Implement the I2C Interface



So we need to adjust two files according to your platform.



### Edit `sensirion_i2c_hal.c`



This file contains the implementation of the sensor communication, which depends on your hardware platform. We provide

function stubs for your hardware's own implementation. Sample implementations are available for some platforms:

[`sample-implementations`](sample-implementations). For Linux based platforms like Raspberry Pi you can just replace the

unimplemented HAL template with the implementation in `sample-implementations/linux_user_space/`:



```

cp sample-implementations/linux_user_space/sensirion_i2c_hal.c ./

```



### Edit `sensirion_config.h`



Skip this part for Linux based platforms since everything is already setup for this case.



Otherwise you need to check if the libraries `` and `` are provided by your toolchain, compiler or

system. If you have no idea on how to do that you can skip this step for now and come back when you get errors related

to these names when compiling the driver. The features we use from those libraries are type definitions for integer

sizes from `` and `NULL` from ``. If they are not available you need to specify the following

integer types yourself:



* `int64_t` = signed 64bit integer

* `uint64_t` = unsigned 64bit integer

* `int32_t` = signed 32bit integer

* `uint32_t` = unsigned 32bit integer

* `int16_t` = signed 16bit integer

* `uint16_t` = unsigned 16bit integer

* `int8_t` = signed 8bit integer

* `uint8_t` = unsigned 8bit integer



In addition to that you will need to specify `NULL`. For both we have a detailed template where you just need to fill in

your system specific values.



Now we are ready to compile and run the example usage for your sensor.



## Compile and Run

Pass the source `.c` and header `.h` files in this folder into your C compiler and run the resulting binary. This step

may vary, depending on your platform. Here we demonstrate the procedure for Linux based platforms:



1. Open up a terminal.

2. Navigate to the directory where this README is located.

3. Run `make` (this compiles the example code into one executable binary).

4. Run the compiled executable with `./sen5x_i2c_example_usage`

5. Now you should see the first measurement values appear in your terminal. As a next step you can adjust the example

   usage file or write your own main function to use the sensor.



# Background



## Files



### sensirion\_i2c.[ch]



In these files you can find the implementation of the I2C protocol used by Sensirion sensors. The functions in these

files are used by the embedded driver to build the correct frame out of data to be sent to the sensor or receive a frame

of data from the sensor and convert it back to data readable by your machine. The functions in here calculate and check

CRCs, reorder bytes for different byte orders and build the correct formatted frame for your sensor.



### sensirion\_i2c\_hal.[ch]



These files contain the implementation of the hardware abstraction layer used by Sensirion's I2C embedded drivers. This

part of the code is specific to the underlying hardware platform. This is an unimplemented template for the user to

implement. In the `sample-implementations/` folder we provide implementations for the most common platforms.



### sensirion\_config.h



In this file we keep all the included libraries for our drivers and global defines. Next to `sensirion_i2c_hal.c` *it's

the only file you should need to edit to get your driver working.*



### sensirion\_common.[ch]



In these files you can find some helper functions used by Sensirion's embedded drivers. It mostly contains byte order

conversions for different variable types. These functions are also used by the UART embedded drivers therefore they are

kept in their own file.