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Custom board with STM32f446rRE: JTAG TDI not successful

70nKA
Associate

Hello everyone,

I am developing a custom PCB and am having a problem while trying to flash the chip.

Before delving further, I need to say that I have made a mistake with routing the JTAG traces to 10pin JTAG connector and may have burnt the chip. I tried to circumvent this by soldering a new chip and using external wires as made a new connector for JTAG 20 to 10pin adapter (https://www.adafruit.com/product/2094) which then connects to ST-LINK/V2:

jtag_circumvent.jpg

After this I would get TDI ERROR message. I tried every possible type of connection available on STM32 ST-LINK Utility and STM32CubeProgrammer. I only maybe haven't tried to lower down the frequency.
I checked the connections made to the chip and everything seemed fine. Every power pin gets correct voltage and there are no short circuits. The power comes through 2 LDOs: 1 is 3.3V and the other is 5V and the power input to the board is 12.5V and around 70mA. The boot pin 1 is connected to ground.

I do not know what to try next besides cutting traces on the board and resoldering them on the board but that does not seem like it would make much difference since rewiring the connector did not work.

 

The only things I think could be wrong would be that the schematics are wrong (beside the JTAG wiring):

- oscillator, decoupling, boot, nreset:

sys.png

- JTAG:

pins.png

- power 12.5V to 5V:

70nKA_0-1742223736249.png

- power 5V to 3.3V:

70nKA_1-1742223794154.png


maybe PCB layout is affecting the connection and the board should have 4 layers instead of 2:

70nKA_3-1742223902647.png

- I think that the marked trace could be troubling as well since the bottom layer should be ground but said trace is "splitting the ground plane and maybe messing up return current path for the communication but maybe I am overreaching with this

This is the gist of it so if someone has had similar problems and could help I would appreciate it :)

1 ACCEPTED SOLUTION

Accepted Solutions

Hi,

Yes that was correct.

It turns out that chip was probably faulty or I have maybe overheated it during soldering. Once a new STM was soldered the connection worked well.

Thank you for your interest.

View solution in original post

2 REPLIES 2
TDK
Guru

Is VCAP voltage around 1.2 V?

 

If you feel a post has answered your question, please click "Accept as Solution".

Hi,

Yes that was correct.

It turns out that chip was probably faulty or I have maybe overheated it during soldering. Once a new STM was soldered the connection worked well.

Thank you for your interest.