Really stupid question about JTAG usage

Thread Starter

Guttalax

Joined Feb 3, 2018
2
I would like to put Xilinx FPGA (XC6SLX25-2FTG256I) and STM32 MCU (STM32F411CCY6TR) on a board and connect them in chain via JTAG. The question is: will there be any conflicts between those devices? To be more exact: will I be able to connect ST-LINK/V2 to the JTAG port and have no trouble with debugging/flashing the MCU? (same with the FPGA + something like "Platform Cable USB II"). The question seems really stupid, but I lack confidence since I've never seen it implemented and actually working. Every answer is appreciated.
 

Teljkon

Joined Jan 24, 2019
92
Why, must you tempt me? All answers are appreciated? :p

My current top responses are:

1.) Ugah ugah ugah bugah!
2.) Kunga ...Kunga....Kunga Golunga! That means Ill have total clarity on my death bed so I have that going for me.

As a novice in electronics

3.) WTF did you just say?

& finally I think you need to run it threw the turbo incabulator instructions below.

4.)

;)
 

MrChips

Joined Oct 2, 2009
19,269
I would like to put Xilinx FPGA (XC6SLX25-2FTG256I) and STM32 MCU (STM32F411CCY6TR) on a board and connect them in chain via JTAG. The question is: will there be any conflicts between those devices? To be more exact: will I be able to connect ST-LINK/V2 to the JTAG port and have no trouble with debugging/flashing the MCU? (same with the FPGA + something like "Platform Cable USB II"). The question seems really stupid, but I lack confidence since I've never seen it implemented and actually working. Every answer is appreciated.
Why make life difficult?
Use a separate connection, one for the Xilinx FPGA JTAG and another for the ST-LINK.
 

ErnieM

Joined Apr 24, 2011
7,992
Daisy chaining JTAGs is possible. Theoretically you can do some awesome stuff way beyond programming or boundary scans.

JTAG Technologies is one company that services these needs. My company uses them, and I believe our maintenance subscription is around $10K/year.

...maybe just leave the devices separated...
 

rsjsouza

Joined Apr 21, 2014
200
You can connect both, but the ST device must comply with the actual JTAG standard (some devices do not fully comply, or they may want to operate in SWD or 2-wire cJTAG) and the ST software must allow configuring the connection and add a bypass to the Xilinx device. This bypass is an extra dummy "device" that is configured with the number of bits specified in the Xilinx documentation.
 
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