ST-Link in P-Nucleo-WB55 board is not working due to the SWCLK wire length.

[KKIM.6]

I have one of P-Nucleo-WB55 and recently bought one more P-Nucleo-WB55 board.

We are using this board to program the STM32WB55VG6YTR microcontroller in our custom board and we have succeeded more than 20 times in programming that microcontroller using ST-LINK in P-Nucleo-WB55.

However, recently we couldn't access either our microcontroller in the custom board or the dummy microcontroller in P-Nucleo-WB55 anymore. In addition, we never succeed in using the new P-Nucleo-WB55 board.

After several trials, we found that the wire length of SWCLK was the reason.

Right now, we only can access the dummy microcontroller in P-Nucleo-WB55 using a jumper pin to connect SWCLK. If we use a normal wire (resistance < 1 ohm), we cannot access even the dummy microcontroller.

This problem is big because we have to program the microcontroller in our custom circuit board.

Does anybody have a similar problem and find a solution?

[Andrew Neil · Accepted solution]

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@KKIM.6 wrote:

we found that the wire length of SWCLK was the reason.

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What made you conclude that it was the length of the wire, specifically?

What length are you using?

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@KKIM.6 wrote:

This problem is big because we have to program the microcontroller in our custom circuit board.

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Obtain a standalone programmer?

eg,

https://www.st.com/en/development-tools/st-link-v2.html

https://www.st.com/en/development-tools/stlink-v3minie.html

etc

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@KKIM.6 wrote:

dummy microcontroller in P-Neucleo-WB55

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I guess this is probably  just lost in translation, but the microcontroller on the board is fully functional - it's not a "dummy".

[KKIM.6]

We can access the dummy microcontroller using a very short jumper pin connecter.

If we replace the jumper pin connecter to a normal 2.54 wire (length < 15 cm, resistance < 1 ohm), we cannot connect to the dummy microcontroller even. 

This problem has happened recently with an old P-Neucleo-WB55 board.

The new P-Neucleo-WB55 board has had this problem from the beginning.

Such a problem wasn't last year.

Is there any update on the CubeProgrammer or any noticeable change?

[Uwe Bonnes]

Try adding more ground wires between the boards. Different Slew behaviour of different chip runs by result in excessive ground bounce