SWD DEBUG Communication STM32H7 ISSUE

[geek12]

Hi everybody,

I'm facing to a strange issue linked to debug using SWD interface with my STLINK V3 for my µC STM32H7. I can download firmware .bin using TeraTerm (using UART RS232).However I'm unable to communicate using STM32Cube IDE in debug mode or STMCube Programmer to erase or load .bin firmware, I get message "no STM32 target detected". By removing the MCU with a new chip, I recover debug/flash functionnality. So my question, is it possible to have just SWDIO and SWCLK pins "damaged" and then no communication in debug mode ? If not, how can I test or erase chip in my case and recover debug functionnality ?

Thanks for your support.

[geek12]

It is a custom board with an STM32H7 MCU and with an UART bootloader. I can flash the MCU using bootloader (TeraTerm) however using DEBUG mode I get error msg(no target found). My application operates correctly when I flash the firmware using the UART bootloader. Also using STMCube programmer I cannot erase the MCU

[MM..1]

Maybe show image  STLINK V3 and schematics how you connect it helps