getting-started-on-the-raspberry-pi.md

Getting Started on the Raspberry Pi 3

This guide assumes you are using the Raspbian image. It should work on other Linux based setups as well, but some details may be different.

We will compile the driver on the Raspberry Pi itself so we assume that the reader has basic knowledge of the Raspberry Pi, shell access to it and that it has a connection to the internet.

The shell code examples below use the following convention:

• Lines starting with # are comments
• Lines starting with $ are commands that should be executed (without the $ prompt)
• Other lines are the expected output from a command

Download Driver

Get the latest release from https://github.com/Sensirion/embedded-uart-sps/releases/latest (sps30-uart-3.1.0.zip for example)

# on the Raspberry Pi
$ wget https://github.com/Sensirion/embedded-uart-sps/releases/download/3.1.0/sps30-uart-3.1.0.zip
$ unzip sps30-uart-3.1.0.zip

Get Port of the Connected Sensor

We need to know the port of the connected sensor. After connecting the sensor via USB run the following:

# on the Raspberry Pi
$ dmesg | grep usb

This should show a line like this:

[   63.545635] usb 1-1.3: FTDI USB Serial Device converter now attached to ttyUSB0

This means the serial device will be reachable as /dev/ttyUSB0.

Adapt the Source Code

Copy the file sample-implementations/linux/sensirion_uart_implementation.c to the base folder:

# on the Raspberry Pi
$ cd sps30-uart-3.1.0
$ cp sample-implementations/linux/sensirion_uart_implementation.c sensirion_uart_implementation.c

Then in sensirion_uart_implementation.c change the line with #define SENSIRION_UART_TTYDEV to match the device you got from the step before.

#define SENSIRION_UART_TTYDEV "/dev/ttyUSB0"

Compile and Run

Now we are ready to compile the example:

# on the Raspberry Pi
$ cd sps30-uart-3.1.0
$ make
rm -f sps30_example_usage
cc -Os -Wall -fstrict-aliasing -Wstrict-aliasing=1 -Wsign-conversion -fPIC -I. -I. -I.  -o sps30_example_usage ./sensirion_arch_config.h ./sensirion_uart.h ./sensirion_shdlc.h ./sensirion_shdlc.c ./sps_git_version.h ./sps_git_version.c ./sps30.h ./sps30.c ./sensirion_uart_implementation.c ./sps30_example_usage.c

When you run the example you should see the following output:

$ ./sps30_example_usage
SPS30 sensor probing successful
FW: 2.2 HW: 7, SHDLC: 2.0
SPS30 Serial: ECBBEEC8D8D650F3
measurements started
measured values:
	1.27 pm1.0
	1.34 pm2.5
	1.33 pm4.0
	1.23 pm10.0
	8.66 nc0.5
	10.11 nc1.0
	10.15 nc2.5
	10.15 nc4.5
	10.15 nc10.0
	0.47 typical particle size

After a minute measurements will be stopped and the sensor will be put to sleep (if the firmware version is newer then 2.0):

measured values:
	1.25 pm1.0
	1.32 pm2.5
	1.30 pm4.0
	1.21 pm10.0
	8.50 nc0.5
	9.92 nc1.0
	9.96 nc2.5
	9.96 nc4.5
	9.96 nc10.0
	0.48 typical particle size

No measurements for 1 minute

After a minute of sleep measurements will be started again:

measurements started
error reading measurement
measured values:
	2.23 pm1.0
	7.80 pm2.5
	12.24 pm4.0
	13.36 pm10.0
	3.90 nc0.5
	12.34 nc1.0
	17.45 nc2.5
	18.54 nc4.5
	18.81 nc10.0
	1.63 typical particle size

Troubleshooting

SPS sensor probing failed

If you get the this error message verify that you copied the Linux sample implementation and that you have the correct device set. See Get Port of the Connected Sensor

Error opening UART. Ensure it's not otherwise used / UART init failed

This happens mostly when the UART device does not exist. See Get Port of the Connected Sensor

Note: It may happen if you unplug and replug the sensor that it gets another device assigned (/dev/ttyUSB1 for example). In that case you either need to change the code and compile again or try to replug it and check if the device changed back.