Debugging the MCU on a NUCLEO-H7A3ZI if 1.8V is selected?

[Bench]

Dear all,

It seems like I actually broke two Nucleo 144 with a H7A3 and H723 after I tried to debug the MCU with the on board debugger and after switching the supply voltage for the MCU to 1.8V (no connection from debugger to MCU possible, even not with 3.3V again).

Is this problem known? If yes, I am wondering, why there is actually the possibility to switch to 1.8V. I found several blog entries that this is not allowed since no level shifters are on the board, but I couldn't find it in the user manuals of the mentioned boards. Did I miss anything?

I really would appreciate your help!

Thank you a lot in advance.

Best regards

[AScha.3]

just from SWD connect 1,8 -> 3,3 V should be no problem, because pins 5V tolerant:

and from schema

https://www.st.com/resource/en/schematic_pack/mb1363-h7a3ziq-d01_schematic.pdf

nucleo144 has level shifters:

 

but NRST could be a problem... so should separate NRST pin. JP3 has to be open.

have/had you any other connections with "high" voltage to H7A3 cpu ?

[Andreas Bolsch]

No problem encountered with Nucleo-H7A3ZI-Q with JP5 set to 1.8V, internal STLink and JP3 closed. Works like a charm. So your problem is most likely not directly related to the Nucleo boards but maybe to external circuit or power supply.

[Bench]

Hallo all,

thank you all for your answers. I will check it again with a new H7 nucleo when it is delivered. Maybe it is the dockingstation that makes problems since I dont have any external circuit attached. I will come back when I tested it!

Good to know that everything should work!

Best regards