STM32H7S78-DK EvalKit Use own Debugger

awakenx1 · ‎2024-07-09

Hello Community,

I want to use an external Debugger (Segger) with this Board. For this the jumper JP3 is left open to hold the STM32F7 (ST-LINK) in RESET.

I attach the Segger to CN8. When connecting I get following message:

Connecting to target via SWD
ConfigTargetSettings() start
ConfigTargetSettings() end - Took 7us
InitTarget() start
SWD selected. Executing JTAG -> SWD switching sequence.
DAP initialized successfully.
Can not attach to CPU. Trying connect under reset.
SWD selected. Executing JTAG -> SWD switching sequence.
DAP initialized successfully.
Connecting to CPU via connect under reset failed.
InitTarget() end - Took 110ms
ConfigTargetSettings() start
ConfigTargetSettings() end - Took 18us
InitTarget() start
SWD selected. Executing JTAG -> SWD switching sequence.
DAP initialized successfully.
Can not attach to CPU. Trying connect under reset.
SWD selected. Executing JTAG -> SWD switching sequence.
DAP initialized successfully.
Connecting to CPU via connect under reset failed.
InitTarget() end - Took 111ms
Cannot connect to target.

So it seems the basic SWD connection works but accessing the core debug registers not. The NRST signal for the STM32F7 is high all the time.

Are there other prerequisites to run an external debugger?

Greetings

Martin

CYANG.1 · ‎2024-11-03

Hi Martin,

Based on your description, open JP3 is not to put F7 in reset, closing JP3 is right action to put F7 in reset.

If you use external debug and suspect embedded STlink conflicts with your external debugger, you can try to remove resistors on debugs signal to bypass the embeded STlink. R55 (NRST), R74(SWDIO), R51 (SWO), R73 (SWCLK).