STM32WB5MMG programming via SWD error no target found

[Jopail12]

Hello folks, 

I've seen a similar topic(link) on this forum, but it had no solution, I'll take my chance and see if you could offer me some tips on how to debug this. 

I've designed a custom "break-out" board for STM32WB5MMG and I'm trying to communicate with the MCU via SWD using a STLINK-V3 MINIE but unfortunately, it's not able to detect the target MCU even though I have connected the MCUs PA13/SWDIO & PA14/SWCLK directly to STLINKV3. 

I've referred to the data sheet on page 16 to the best of my ability on how to design the breakout board but still I am not able to communicate with the MCU. (see schematic below)

Am I missing something here? 

Any tips would be greatly appreciated thanks!

[FilipKremen]

Hello,

is your power supply stable?

How is your boot pin connected (floating, tied to low/high)?

Please also make sure that the SWD wires are short as possible.

I also noticed from the schematic that VDDUSB isn't connected, according to the datasheet it must be connected to VDD or ground when not used.

Best regards,

Filip Kremen

[Jopail12 · Accepted solution]

Hello Filip Kremen,

Thank you for your response much appreciated!

After further investigation, I discovered that the issue stemmed from the reflow assembly of the MCU onto the custom board. Specifically, several pins on the outer ring of the package were not making proper contact with the PCB pads during the initial reflow process. This poor soldering was preventing the STLINK from establishing communication with the target.

I performed the reflow again, ensuring full pad contact and alignment. That resolved the issue and I'm now able to successfully upload firmware and debug the MCU.

Thanks again for your guidance!

Best regards,

Eldon