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Unable to Connect to Target STM32F412CEU6

Hi. I have a simple custom board with STM32F412CEU6. I can't connect to the MCU using the ST-LINK through SWD.
Here is the circuit.

I have tried different settings, still getting the error.

I verified all the voltages and settings. They all seem ok.

I also measured the signals on SWD.

The only thing is the voltage level on SWD for the 0-V level looks suspicious.

Can anyone help me to find the issue?

Regards,
Caner
Alp Electronix

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Best answer by caneralp

Thanks for the suggestions.

1- There is a 4.7uF cap.

I just found the issue. I connected the VDD of the debugger pin to the same voltage of the board, now I can connect to the target.

Regards,

Caner

ST Technical Moderator

Hello @caneralp and welcome to the community,

What is the value of the capacitor connected to VCAP pin?

According to the AN4488 "Getting started with STM32F4xxxx MCU hardware development":

1- You need a 4.7uF capacitor on VCAP1 pin.

2- And a 4.7uF as decoupling capacitor connected to VDD not 2.2uF.

PS:

1- No need for NRST pullup resistor, as there is one internal in the chip.

2- Please use STM32CubeProgrammer to connect to the MCU instead of STLINK utility as it's a deprecated tool.

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