Nucleo-144 (F756ZG) stopped working after cut-off ST-Link

[bogus]

Hello, I recently bought Nucleo-144 board (variant F756ZG) to one of my project. I used DFU to upload firmware and external power supply using VIN pin (7.5 VDC). It works perfect until I decided to remove ST-Link part to reduce board size. After that it won't work anymore (no Serial COM, no Ethernet). Could someone help me what I am doing wrong? Maybe I should reconfigure jumpers but I don't know which. Below I attached photo of board.

Many thanks for help.

[Tesla DeLorean]

No Serial COM? You mean from the ST-LINK/V2-1 VCP connection?

You can find a schematic via the "CAD Resources" page for the product

Check where the 5V source comes from in the VIN case, because the regulator is almost certainly a 3V3 one, not a means of getting 5V from the 7.5V you're injecting.

[AScha.3 · Accepted solution]

Hi,

just look, if you still have a clock on the cpu....

see circuit:

Clock coming from MCO , st-link, but you cut it away: so change solder bridge SB8/9 (close) , sb149 cut.

And set your HSE to crystal , 8MHz . (If you didnt this.)

And check: is crystal and C37/38 really there ? Otherwise install , solder 8MHz crystal + 2x 4p7 there.

From pic: X3 not there, so you have to solder...or just for check/run : set it on HSI , to get it working without crystal.

[Tesla DeLorean]

The Ethernet has it's own TCXO / Crystal

But yes the HSE might be an issue

Instrument code, output something, or turn on RED LED if you go off and die in Error_Handler()

Have something in HardFault_Handler() too

[Andrew Neil]

So what debugging have you done to see what is happening?

You can still use the broken-off ST-Link to debug and/or as a VCP - you just have to re-make all the necessary connections with wires.

As the others have said, by default the Target MCU gets its clock from the ST-Link - so you're also going to have to do something about your clock source ...

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@bogus wrote:

Maybe I should reconfigure jumpers but I don't know which. Below I attached photo of board.

Many thanks for help.

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The User Manual describes all the jumpers and, as @Tesla DeLorean said, you can also look at the schematics...

[bogus]

You are of course right - Clock was the problem. My *** mistake, I was too focused on searching problem with power supply...

After soldering missing components board is alive again.

Thanks to everyone for help.