jerryscript/targets/zephyr

About

This folder contains files to integrate JerryScript with Zephyr RTOS (https://zephyrproject.org/).

How to build

1. Preface

1. Directory structure

Assume harmony as the path to the projects to build. The folder tree related would look like this.

harmony
  + jerryscript
  |  + targets
  |      + zephyr
  + zephyr-project

2. Target boards/emulations

Following Zephyr boards are known to work: qemu_x86, qemu_cortex_m3, frdm_k64f. But generally, any board supported by Zephyr should work, as long as it has enough Flash and RAM (boards which don't have enough of those, will simply have link-time errors of ROM/RAM overflow).

2. Prepare Zephyr

Follow this page to get the Zephyr source and configure the environment.

If you just start with Zephyr, you may want to follow "Building a Sample Application" section in the doc above and check that you can flash your target board.

Remember to source the Zephyr environment as explained in the zephyr documenation:

cd zephyr-project
source zephyr-env.sh

export ZEPHYR_GCC_VARIANT=zephyr
export ZEPHYR_SDK_INSTALL_DIR=<sdk installation directory>

3. Build JerryScript for Zephyr QEMU

The easiest way is to build and run on a QEMU emulator:

For x86 architecture:

make -f ./targets/zephyr/Makefile.zephyr BOARD=qemu_x86 run

For ARM (Cortex-M) architecture:

make -f ./targets/zephyr/Makefile.zephyr BOARD=qemu_cortex_m3 run

4. Build for a real board

Below, we build for NXP FRDM-K64F board (frdm_k64f Zephyr board identifier). Building for other boards is similar. You are expected to read Supported Boards section in the Zephyr documentation for more information about Zephyr's support for a particilar board, means to flash binaries, etc.

# assuming you are in top-level folder
cd jerryscript
make -f ./targets/zephyr/Makefile.zephyr BOARD=frdm_k64f

At the end of the build, you will be given a path to and stats about the ELF binary:

...
Finished
   text	   data	    bss	    dec	    hex	filename
 117942	    868	  24006	 142816	  22de0	build/frdm_k64f/zephyr/zephyr/zephyr.elf

Flashing the binary depends on a particular board used (see links above). For the FRDM-K64F used as the example, you should copy the raw binary file corresponding to the ELF file above (at build/frdm_k64f/zephyr/zephyr/zephyr.bin) to the USB drive appearing after connecting the board to a computer:

cp build/frdm_k64f/zephyr/zephyr/zephyr.bin /media/pfalcon/DAPLINK/

To interact with JerryScript, connect to a board via serial connection and press Reset button (you first should wait while LEDs on the board stop blinking). For frdm_k64f:

picocom -b115200 /dev/ttyACM0

You should see something similar to this:

JerryScript build: Aug 11 2021 16:03:07
JerryScript API 3.0.0
Zephyr version 2.6.99
js>

Run the example javascript command test function

js> var test=0; for (t=100; t<1000; t++) test+=t; print ('Hi JS World! '+test);
Hi JS World! 494550

Try a more complex function:

js> function hello(t) {t=t*10;return t}; print("result"+hello(10.5));