Flashing STM32 From CM4

In order to use the Raspberry Pi CM4 to upload firmware to the STM32, we need a custom version of OpenOCD which can use the CM4’s GPIOs to connect to the STM32’s SWD interface.

Step 1: Building OpenOCD

Execute the following commands in order to install the dependencies, build and install OpenOCD:

sudo apt install automake autoconf build-essential libtool libftdi-dev libusb-1.0-0-dev texinfo pkg-config rpi.gpio-common curl
git clone https://github.com/raspberrypi/openocd.git --recursive
cd openocd
./bootstrap
./configure --enable-ftdi --enable-sysfsgpio --enable-bcm2835gpio
make -j$(nproc)
sudo make install

Step 2: Get the OpenOCD Configuration

Fetch the configuration and install it globally for OpenOCD to find it:

sudo curl -o /usr/local/share/openocd/scripts/interface/xcore.cfg https://core.x-tech.online/downloads/openocd-xcore.cfg

Step 3: Upload a binary

Get a binary (.elf format) and upload it to the STM32 like this:

openocd -f interface/xcore.cfg -f target/stm32h7x.cfg -c "program your-binary.elf verify reset exit"

The firmware should be uploaded and the program should be running.

Debugging via remote GDB

In order to debug the program on your xCore board, run the following command:

openocd -f interface/xcore.cfg -f target/stm32h7x.cfg -c "bindto 0.0.0.0"

Then connect your favorite IDE to port 3333 to upload and debug using GDB