Cannot Flash STM32WB55CEU6

[YamiTheWitch]

Hello, I have a custom board with a STM32WB55CEU6 and I am trying to programm it through a Nucleo STLink with SWD. The onboard Nucleo CPU is detected and works fine if I add the jumpers, and I can program a different STM32 board with the jumpers removed as well, so the STLink is functional.

It fails when trying to connect to the STM32 saying it's unable to detect the Device ID, so no SWD communication happens at all. I have connected SWCLK, SWIO, NRST and GND and checked the polarity multiple times. I also checked with a multimeter, and there is connectivity between the pins. I used a 10cm Dupont Jumper and the traces on the board are around 3cm long. Boot0 is tied to GND. Supply voltage is a clean 3V3 and I am using the internal SMPS, where VDDSMPS is at 0.97V if I plug it in. So I think the STM32 is powered and operational, just not able to connect. 

I don't really know what else could be going wrong on the board, so I came here to ask for help. 

[mfgkw]

Did this board ever work?

P.S.: The ST-Link can be updated. Is it's FW new enough to know the STM32WB55CEU6?

[YamiTheWitch · Accepted solution]

I fixed this issue on my own. I missed a VDD connection to one of the SMPS caps, no clue how that still created a voltage. I bodge fixed it with some soldering. It's flashing and booting now, and is playing a blinking test code just fine. Thanks for the reply anyways. Also yes, I updated the STLink, forgot to add that to the original post.

[Andrew Neil]

Good to hear! Now please mark the solution on your post which provided the answer - not this one.