Get and compile a Zephyr firmware

Difficulty: Medium

Duration: 20 minutes

Description: Zephyr is a real-time operating system designed for the Internet of Things (IoT). The aim of this tutorial is to understand how to setup your environment and how to compile a Zephyr firmware. Note that Zephyr can be used with the following IoT-LAB nodes: nRF52DK, nRF52840DK, nRF51DK, BBC micro:bit, FRDM-KW41Z, Arduino Zero, ST B-L072Z-LRWAN1, ST B-L475E-IOT01A.
The Zephyr SDK, which is required to build the firmwares, is provided by the SSH frontend of each IoT-LAB site.

Setup your environment by cloning the iot-lab repository from GitHub

ssh <login>@saclay;.iot-lab.info
<login>@saclay~$ git clone https://github.com/iot-lab/iot-lab.git
Cloning into 'iot-lab'...
...
<login>@saclay~$ cd iot-lab
<login>@saclay:~/iot-lab$ make

  Welcome to the IoT-LAB development environment setup.

  targets:
	setup-aggregation-tools
	setup-cli-tools
	setup-contiki
	setup-iot-lab.wiki
	setup-oml-plot-tools
	setup-openlab
	setup-riot
	setup-wsn430
	setup-zephyr


	pull

Setup Zephyr target

<login>@saclay:~/iot-lab$ make setup-zephyr
make setup-zephyr
git clone --depth https://github.com/zephyrproject-rtos/zephyr.git parts/zephyr
Cloning into 'parts/zephyr'...
...
<login>@saclay:~/iot-lab$ cd parts/zephyr

Setup the environment variables required to use the Zephyr SDK:
```
<login>@saclay:~/iot-lab/parts/zephyr$ source /opt/zephyr.source
```
This must be done in each new shell. To have the SDK setup everytime, the command above can be added at the end of your ~/.bashrc file.
Setup the ZEPHYR_BASE environment variable:
```
<login>@saclay:~/iot-lab/parts/zephyr$ source zephyr-env.sh
```
This must be done in each new shell. To have ZEPHYR_BASE correctly setup everytime, the command above can be added at the end of your ~/.bashrc file (use an absolute path to zephyr-env.sh).

Now that everything is in place, let’s build our first hello_world firmware. This firmware is based on the sample provided in parts/zephyr/samples/hello_world. The sample will be built for the nRF52DK node, which corresponds to the board nrf52_pca10040 in Zephyr.

<login>@saclay:~/iot-lab/parts/zephyr$ cd samples/hello_world
<login>@saclay:~/iot-lab/parts/zephyr/samples/hello_world$ mkdir build-nrf52
<login>@saclay:~/iot-lab/parts/zephyr/samples/hello_world$ cd build-nrf52
<login>@saclay:~/iot-lab/parts/zephyr/samples/hello_world/build-nrf52$ cmake -DBOARD=nrf52_pca10040 ..
<login>@saclay:~/iot-lab/parts/zephyr/samples/hello_world/build-nrf52$ make

The generated firmware is located in the zephyr/samples/hello_world/build-nrf52/zephyr directory:
```
<login>@saclay:~/iot-lab/parts/zephyr/samples/hello_world/build-nrf52$ ls zephyr/zephyr.{hex,bin,elf}
zephyr/zephyr.bin  zephyr/zephyr.elf  zephyr/zephyr.hex
```
Use the *.elf file to flash the nodes using the IoT-LAB tools (webportal or cli-tools)

Here is a table containing the mapping between node names with IoT-LAB names and Zephyr names:

Node name	IoT-LAB name	Zephyr name
nRF52DK	nrf52dk	nrf52dk_pca10040
nRF52840DK	nrf52840dk	nrf52840_pca10056
nRF51DK	nrf51dk	nrf51_pca10028
BBC micro:bit	microbit	bbc_microbit
NXP FRDM-KW41Z	frdm-kw41z	frdm_kw41z
Arduino Zero	arduino-zero	arduino_zero
ST B-L072Z-LRWAN1	st-lrwan1	b_l072z_lrwan1
ST B-L475E-IOT01A	st-iotnode	disco_l475_iot1

Build the hello_world firmware for each of the nodes listed above.

Congratulations, you have completed the tutorial!