STM32F405 Can not connect to target

[Mhushki]

Hello All, I Hope you are well.

I am facing a problem that I spent A LOT of time on. I designed a custom board featuring the STM32F405RGT6 but i cannot connect to it at all.. I will attach the schematic and the board's pictures below. (The schematic is a PDF where I attached the sheet of the MCU's circuitry only there are other sheets for other parts of the board)

 

Things to mention:
1- I've assembled the board myself (But i checked the connectivity and voltages on the necessary nodes by a multimeter and i tested on the chip's pins not on the PCB pads and got the following:

-VDD on all VDD pins are 3.31V (measured directly on the pins)

-VDDA is also supplied by the same source with around 3.31V (measured directly on the pins)

-Vcap1 and Vcap2 are both 1.26V (measured on the the two Caps of 2u2 value)

-Reset Pin is 3.31V

)

2- I got suspicious about the SWD pinout that i did so i used an adapter and a Nucleo board's ST-Link to connect to my board where I measured the resistance between the SWD Pins and the Nucleo board and all are connected with reasonable resistance (Under 10 Ohms) (I got so desperate of the cause that I replaced the termination resistors of 49R9 with 0Ohms ones)

3- I got in both modes of Boot0 being Low and High. (Boot1 is floating would that cause the lack of connectivity?)

 

Am I missing something?!

Any kind of help would be much much appreciate. Thank you in Advance.

 

[Mhushki]

@Tesla DeLorean  I commented few days ago on another post and i was advised by you to post my issue separately..

any idea sir? Thanks in advance :folded_hands:

[AScha.3]

Hi, 

boot1 floating ... why ??

So you can not use bootloader, boot0 has to be low .

 

[Mhushki]

Thank you for your reply, 

I've soldered a wire and i pulled boot1 low through a 10k resistor.. and then tried to pull it high .. but with the same result.. would this mean that my chip is dead? 

Would it be dead even if i see the reset pin voltage as expected and both vcaps1&2 showing proper voltage? What do you think is the issue here?

[AScha.3]

Seems everything ok (if boot0 lo ! ) , should work.

Maybe you puzzeled the swd pins ? (mirrored pinout .... i have workmate, that "loves" to do this. But always 100% sure, he did right. )

Try connection with CubeProgrammer ... best, to see, whats going on.

Show, what it tells or shows.

[Mhushki]

Hello again, 

Vdd on the ST-link is 3.38V and this is what i got in the CubeProgrammer:

Should i just give up and replace the chip when i get some stock? it doesn't seem dead to me but it's driving me crazy why can't I connect to it!!

[AScha.3]

Hi,

it tells : 

So what you use here ? a st-link ? or a nucleo-F446 board ??

[Mhushki]

I'm using the st-link part of the nucleo board (stm32F446RE) (and it'sworth mentioning that the actual chip F446 is not on the board anymore after it got burned few weeks ago) ,, I read in ST's application note (UM1724) that there are two jumpers i can take them off and use the St-link to program external chips by the SWD header 

And as i mentioned in one of the previous replies, that using the same method successfully identified the stm32f103 on a bluepill board with no issues.