JTAG connection with STM32F7

Aaron Pica · ‎2017-03-03

Posted on March 03, 2017 at 16:25

I'm using a STM32F7 MCU with a JTAG connection (4-pins used). The schematic is attached. It uses the

http://www.keil.com/support/man/docs/ulinkpro/ulinkpro_jtag_10pin_swm.gif

, and it's connected to a ST-LINK using the

https://www.olimex.com/Products/ARM/JTAG/ARM-JTAG-20-10/

.

The SWD works correctly, but the JTAG can't be connected (I'm using the ST-LINK Utility). Also, I have already used the same schematic for a STM32F2, and it connects successfully using JTAG.

Is there any difference/limitation with the STM32F7 MCU? Any clue of what can happen?

Thank you

#stm32f7 #stlink #jtag-dp #jtag

Uwe Bonnes · ‎2017-03-04

Posted on March 04, 2017 at 23:57

Can yout test with another Adapter or with another board? Mostly error are done by the user. Fundamental Errors in crucial of the parts circuit may happen, as with the Ethernet PHY in F767 rev1, but all in all are rather seldom. I suspect JTAG to work on the F767, or otherwise it would be documented in the errate.

S.Ma · ‎2017-03-05

Posted on March 05, 2017 at 12:08

Is there a specific reason to use JTAG vs SWD? Performance-wise SWD is usually good enough for debugging with 2 or 3 IOs (if SWO printf debug feature is used). Maybe missing pull-ups on JTAG lines?

Aaron Pica · ‎2017-03-06

Posted on March 06, 2017 at 12:19

Thank you for the reply.

I've tried with other boards without any success.

Aaron Pica · ‎2017-03-06

Posted on March 06, 2017 at 12:24

Thank you for the reply.

There isn't any reason to use JTAG, but I was wondering why it's not working and if there is a hardware error in the design.

The

http://www.st.com/content/ccc/resource/technical/document/application_note/b0/5c/ba/b2/cb/10/41/dd/DM00164549.pdf/files/DM00164549.pdf/jcr:content/translations/en.DM00164549.pdf

explains that STM32F7 had internal pull-ups/downs on the JTAG pins, so 'Having embedded pull-ups and pull-downs removes the need to add external resistors'.

Uwe Bonnes · ‎2017-03-06

Posted on March 06, 2017 at 12:48

That other boards don't work neither indicates an error on your side...