LiteX and Zephyr OS blinky Demo

This page describes steps to build LiteX SoC with VexRiscv CPU and run Zephyr OS blinky demo on GMM-7550 module with USB 3 adapter and memory modules.

Building LiteX SoC

Get LiteX board sources 

git clone https://github.com/GMM-7550/litex-boards.git
cd litex-boards
git checkout gmm7550

activate Python virtual environment with LiteX installed 

. ~/Work/LiteX/bin/activate

Build SoC 

python ./litex_boards/targets/gmm7550_usb3.py --build --cpu-variant="standard" --with-async-ram

Building Zephyr OS blinky Demo

Building Zephyr OS require the following tools to be installed and properly configured:

  • Zephyr OS sources (https://github.com/zephyrproject-rtos/zephyr) and RISC-V SDK
  • west Zephyr’s meta-tool (https://docs.zephyrproject.org/latest/develop/west/index.html)
  • uv Python package and project manager (https://github.com/astral-sh/uv)
git clone https://github.com/GMM-7550/gmm7550-zephyr.git
cd gmm7550-zephyr
make

Running blinky demo on GMM-7550

Program FPGA configuration to the module 

# Connect to the GMM-7550/RP2040 control CLI
~$ picocom -q -b 115200 /dev/ttyACM1

GMM-7550 Control CLI

Version    : 0.8.2
Git hash   : e34e7fd42ab86e61b12e2f9affaf41872b26d1c1
Build time : 2026-03-05 01:43:49

> on

> rst 1

> mux 2
SPI Mux configuration is 2

^A^X

~$ gmm7550_spi.py -c litex-boards/build/gmm7550/gateware/gmm7550.bit

Running the demo 

# Create a link to Zephyr OS blinky demo
~$ ln -s gmm7550-zephyr/build/zephyr/zephyr.bin

# Launch LiteX terminal -- it will start the board automatically
~$ litex_term --kernel ./zephyr.bin /dev/ttyACM0
...