Unable to connect to ST LINK

[JGoh.1]

HI,

I have a custom board STMWB55CGU6. I have connected it to a ST-LINK V2 to try to debug it. I have connected the correct pins (GND, NRST, SWDIO and SWCLK) but the STLINK is unable to detect the PCB. It shows the error as shown in the picture below and I have tried the method of connect under reset but to no avail also.

Any ideas on this problem? Due to the fact that I am unable to detect the Microcontroller, I am unable to neither program or debug it.

[LMI2]

With STM32 ST-LINK Utility you could try program under reset or something such. Has your CPU power and is board wired correctly.

[S.Ma]

WB seems special case. usually the STLink maybe monitoring the MCU Vdd to confirm the chip is powered.

Also if the chip is running clock stop mode (low power mode) then the debug link will have more challenges to operate.

If there is a boot pin, you can do a manual reset rising edge with boot pin to start the bootloader (no power save mode) so you can reflash it.

This might not be enough...