Debugging the Lora-STM32WL-devkit: Open On-Chip Debugger failed

[Volker]

Two Remarks:

1. Launching the debugger fails with a probability of about 50%.

2. OpenOCD.exe which came with STM32CubeIDE 1.10.0 does not work:

C:\ST\STM32CubeIDE_1.10.0\STM32CubeIDE\plugins\com.st.stm32cube.ide.mcu.externaltools.openocd.win32_2.2.100.202206011703\tools\bin\openocd.exe -f interface/cmsis-dap.cfg -c "cmsis-dap vid_pid 0x15ba 0x0044" -c "transport select swd" -c "adapter speed 2000" -f "target/stm32wlx.cfg"
Open On-Chip Debugger 0.11.0+dev-00449-g53fa0f7 (2022-06-09-09:42) [https://github.com/STMicroelectronics/OpenOCD]
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
cmsis-dap <cmd>
  cmsis-dap cmd
  cmsis-dap info

[Volker]

I tried using the openOCD.exe which comes with STM32CubeIDE 1.10.0. This version just issues a message and does nothing:

 C:\ST\STM32CubeIDE_1.10.0\STM32CubeIDE\plugins\com.st.stm32cube.ide.mcu.externaltools.openocd.win32_2.2.100.202206011703\tools\bin\openocd.exe -f interface/cmsis-dap.cfg -c "cmsis-dap vid_pid 0x15ba 0x0044" -c "transport select swd" -c "adapter speed 2000" -f "target/stm32wlx.cfg"
Open On-Chip Debugger 0.11.0+dev-00449-g53fa0f7 (2022-06-09-09:42) [https://github.com/STMicroelectronics/OpenOCD]
Licensed under GNU GPL v2
For bug reports, read
        http://openocd.org/doc/doxygen/bugs.html
cmsis-dap <cmd>
  cmsis-dap cmd
  cmsis-dap info

[LubOlimex]

I believe the support for STM32wlx chips was added in OpenOCD 1.11.0, so it is expected to have problems with OpenOCD 1.10.0.

[Volker]

Has this problem solved in the meantime. Without software the Lora-STM32WL-devkit is pretty useless, or?

[LubOlimex]

No real progress had been made. I managed to run it through the STM32CubeIDE like you, thanks for this I didn't know it is possible, but unfortunately haven't found a solution. It is quite likely that the problem is in some compatibility between the CMSIS firmware and OpenOCD. I am not sure when it occurred since I've tested it in the past and it worked just fine. I will also test with IAR EW and see if it works there.

It is not as useful as it should be since the real-time debugging doesn't seem to work reliably (here it works sometimes, sometimes it fails) but it is not useless either - it still can be used relatively well for programming (albeit slow without the flash loader). Just make sure to reduce the work area in the stm32wlx.cfg config.

Yet, LoRa-STM32WL-DevKit is open-source hardware project and the firmware it runs is also open-source (modified dap42 https://github.com/devanlai/dap42), so even if we can't solve it, it is possible to try to fix it yourself.

Edit: I found some old revision boards and they behave similarly to the latest revision so it is not due a change in hardware.

[Volker]

Forget the onboard debugger interface. Use ST-Link/V2.

Connection to ST-Link/V2:
Remove the pins 1 and 2 of CON2 of the Modul BB-STM32WL sitting on the LoRa-STM32WL-DevKit. This disconnects the signals swclk and swdio from the base board.
Connect:
pin1 (swclk) with pin 9 (TCK_SWCLK) of ST-Link/V2
pin2 (swdio) with pin 7 (TMS_SWDIO) of ST-Link/V2
pin7 (+3.3V) with pin 1 (+3.3V in)  of ST-Link/V2
pin6 (NRST)  with pin 15 (NRST)    of ST-Link/V2
GND on baseboard with pin 20 (GND)  of ST-Link/V2

Debugger: Select AUtostart local GDB server, localhost, port 61234
Debug probe: ST-Link (ST-Link GDB server)
Select SWD
Frequency: Auto
Access port: 0-Cortex-M4
Connect under Reset
Verify flash download
Enable live expressions

ST-Link/V2 works very reliable.