FreeRTOS 10 on the STM32L432 of the NUCLEO-L432KC

The freertos10-stm32l432-nucleol432kc platform targets the STM32L432 microcontroller, an Arm Cortex-M4, running FreeRTOS 10 on the NUCLEO-L432KC board, representative of the small Arm-based controllers found in instrumentation and robotics. It is built with arm-none-eabi-gcc, and the program is written into the flash of the microcontroller.

The GDB server

The board is debugged through its ST-LINK probe with ST-LINK_gdbserver, which is part of STM32CubeCLT and runs on the host. It is started with the SWD interface, port 61234, the core 0, and the folder of the STM32CubeProgrammer that comes with STM32CubeCLT:

$ CLT=/opt/st/stm32cubeclt_1.19.0
$ $CLT/STLink-gdb-server/bin/ST-LINK_gdbserver -d -p 61234 -m 0 -e \
    -cp $CLT/STM32CubeProgrammer/bin

The option -e keeps the server running between debugging sessions. Without it the server exits when the debugger disconnects, and every new session, or every test, needs the server started again.

Debugging

A debugging session of the Termina extension connects the debugger to the server, as the Debugging chapter describes. monitor reset resets the microcontroller and leaves the core halted, and load writes the program into the flash. Since the code runs from flash, the breakpoints are hardware ones, and the Cortex-M4 has six of them.

Running tests

Before each run of a test, and before each case with --isolated, the runner resets the microcontroller with monitor reset and writes the binary of the test with load. It uses three of the hardware breakpoints, so three remain for a debugging session on the binary of a test.