Awesome
Sensirion Raspberry Pi I2C SDP Driver
This document explains how to set up the SDP sensor to run on a Raspberry Pi using the provided code.
<center><img src="images/SDP8xx.png" width="250px"><img src="images/SDP3x.png" width="250px"></center>Click here to learn more about the SDP3x Sensor Evaluation Kit.
Click here to learn more about the SDP8xx series Sensor Evaluation Kit.
Setup Guide
Connecting the Sensor
Your sensor has the four different connectors: VCC, GND, SDA, SCL. Use the following pins to connect your Sdp:
Sdp | Raspberry Pi |
---|---|
VCC | Pin 1 |
GND | Pin 6 |
SDA | Pin 3 |
SCL | Pin 5 |
Setting sensor address
Depending on whether you connect a SDP3x or SDP8xx configure the correct i2c address in sdp_i2c.h (SDP_I2C_ADDRESS).
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
-
Open a terminal
-
Navigate to the driver directory. E.g.
cd ~/raspberry-pi-i2c-sdp
-
Run the
make
command to compile the driverOutput:
rm -f sdp_i2c_example_usage cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -o sdp_i2c_example_usage sdp_i2c.h sdp_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 sdp_i2c_example_usage.c
-
- Test your connected sensor
-
Run
./sdp_i2c_example_usage
in the same directory you used to compile the driver.Output:
Product number: 0x03020b01 Serial Number: 1902067650 Differential pressure: -0.17 Pa Temperature: 28.80 °C Differential pressure: -0.03 Pa Temperature: 28.80 °C Differential pressure: -0.03 Pa Temperature: 28.80 °C Differential pressure: -0.03 Pa ...
-
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
Error executing sdp_get_serial_number(): -1
Error executing sdp_read_product_identifier(): -1
Error executing sdp_start_continuous_measurement_with_diff_pressure_t_comp_and_averaging(): -1
Error executing sdp_read_measurement(): -1
then go through the below troubleshooting steps.
- 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 ./sdp_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 your-user i2c
Adding user `your-user' to group `i2c' ...
Adding user your-user 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 reasoably 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