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ABuja.1
Associate II
November 5, 2020
Solved

Can't connect to STM32F412 with SWD

  • November 5, 2020
  • 1 reply
  • 1486 views

Here is my schematic and board. I'm wondering if someone can verify that I have everything that's needed on the stm32f4. I can't connect with SWD to the core. My JLink tries multiple times and fails. When I press the reset button on my board the JLink's LED turns red so it seems that the connection between my board and the JLink is correct.

I've found a mistake in my crystals' capacitor values, but I don't think that should cause this issue?

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Best answer by TDK

Big issues:

VSSA needs grounded.

VDDA needs connected to VDD.

Smaller issues:

The capacitor on VCAP should be 2.2uF or 4.7uF.

The load caps for X1 (8MHz crystal) almost certainly shouldn't be 0.1uF. Probably closer to 10uF. Probably true for X2 caps as well.

1 reply

TDK
TDKBest answer
November 5, 2020

Big issues:

VSSA needs grounded.

VDDA needs connected to VDD.

Smaller issues:

The capacitor on VCAP should be 2.2uF or 4.7uF.

The load caps for X1 (8MHz crystal) almost certainly shouldn't be 0.1uF. Probably closer to 10uF. Probably true for X2 caps as well.

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ABuja.1
ABuja.1Author
Associate II
November 5, 2020

Thanks, I'll try connecting VSSA and VDDA and see if it works.

Are you sure about the load cap values? In the datasheet it seems to recommend 5pF to 25pF

TDK
November 5, 2020
Oops. I meant 10pF, not 10uF, for X1 caps. Not real sure for X2, but definitely in the pF range.
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