STM32F215 SWD connexion impossible

neoirto · ‎2014-11-11

Posted on November 11, 2014 at 14:32

Hi all,

Our new board arrived yesterday but I can't even connect via SWD. Could you please help us to find the problem ?

BOOT0 = pull down via external 10K resistor

BOOT1 = direct connexion to GND

SWD are well routed, but I can't see any level on the SWD pins : 0V on every pin.

When the ST-Link v2 is acting on JTRST : no response from MCU.

The same problem is encountered on 2 different boards.

We tried with NRST pin floating, or with NRST in direct connection to VDD : same behaviour...

What do you think about please ?

[EDIT] = no response too by USART1 bootloader...

Tesla DeLorean · ‎2014-11-11

Posted on November 11, 2014 at 17:07

Check you can see 1.25V on your VCAP pins, check VSSA, and that you have the part correctly orientated.

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neoirto · ‎2014-11-11

Posted on November 11, 2014 at 17:34

OMG !

We routed VCAP_1 and VCAP_2 directly on GND, exactly the same as on the STM32F1, with 2.2 uF decoupling capacitor. I'm afraid it's a mistake, isn't it ?

As explained p8 of

http://www.st.com/web/en/resource/technical/document/application_note/DM00033267.pdf

it should not ?

Tx again Clive

[EDIT] = is the MCU fried ?

megahercas6 · ‎2014-11-11

Posted on November 12, 2014 at 06:51

VCAP is for internal LDO, so your m3 core don't have any supply. if you cut tracks, with no decoupling maybe you will be able to connect.

STM32 is quite robust MCU, it should handle this kind of abuse