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I am really confused and helpless. I made a custom PCB with the STM32F446VE (LQFP100) chip and got it programmed (SWD).

After that I made a second PCB where I wanted to solve some Problems regarding PWM Output. I kept everything about the microcontroller and ist programming the same, but now I cannot program it anymore, but changed the PCB manufacturer, because the new one has black matte for the same price ^^

I changed the layout so that i have a smaller pcb Footprint, but kept the programming part and the microcontroller the same.

(I made another PCB for another Purpose with the same microcontroller and progamming part, which works flawlessly.)

I tried everything to make it work, but failed.

My results so far:

What works

-the programmer (ST-Linkv2) works

-the cable works

-the Swclk Signal works as well

-the chip isn't burned, soldered wrong or malfunctioning

-there are no shorts on the PCB

-there are no solder bridges

What doesnt work

-the IDE (Atollic) doesn't recognize the chip

-the stlink Utility doesnt recognize the chip

-the swdio and reset signals don't change when I connect to the chip via the programmer and stlink Utility

What I'm not sure of:

According to the reference design, i need a smoothing capacitor of 10uF on the reset line to GND, which I didn't include. But on the other PCB's it worked without it. It doesn't seem to be the root cause, because the swdio line doesn't change as well.

Did anyone Encounter the same Problem?

Do you have any suggestions or tips how to find the root cause?

The only option I have right now is to change the layout and just hope and pray for the best.

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    \$\begingroup\$ Inspect the board carefully under magnification. Verify all the basic rules of using the chip, particularly power decoupling and power to every pin, anything required to support an on-chip regulator, deterministic state of the boot mode pin, etc. If you can change the boot mode pin see if you can get the serial bootloader to answer. Get a hot air tool and swap the chip to a good board or a good chip to the board, also check for any issues under the IC package while you have it off. Voting to close as questions seeking an open-ended list of ideas don't really fit the stack exchange model. \$\endgroup\$ – Chris Stratton Aug 2 at 16:25
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    \$\begingroup\$ I'm assuming you have assembled only one unit of the failing board. You can't blame the design right away if a single board fails. There is so much that can go wrong in the assembly. @ChrisStratton's suggestion to swap the SoCs is a good one. I would start there. Another option is to assemble a new board from scratch (I'm assuming you haver multiple naked PCBs). \$\endgroup\$ – joribama Aug 3 at 4:02
  • \$\begingroup\$ Thank you I already soldered 3 SOC's on it and it didnt work, including a brand new one and a working one. I have checked that it has power on every power pin and if every Ground pin is connected to GND @ChrisStratton this is my first Question on stackexchange. I will close the Question if someone else thinks the same \$\endgroup\$ – cacciu Aug 4 at 10:28

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