External JTAG / J15 for PS on Arty Z7

[mete]

Hello,

I would like to access PS through an external JTAG probe. The JTAG lines on this board is connected to J15 but J15 is staying exactly on the opposite side of JA connector and I believe it is not connected anything else. How can I use that ? Should I demount/cut the JA connector and solder a 6-pin header ? 

Probably related to my question above, in the reference manual, it is said "To access the PS over JTAG while in independent JTAG mode, users will have to route the signals for the PJTAG peripheral over EMIO, and use an external device to communicate with it.". Does this mean I can route the JTAG pins of PS (I think this is PJTAG) to an IO pin on the board that I can access, if I short the JP2 JTAG that enables independent JTAG mode ?  

Thanks,

Mete

[Ana-Maria Balas]

Hello @mete,

We must clarify the difference between independent JTAG mode and Cascade JTAG.

The Micro USB and J15 header uses Cascade JTAG.

Through JP2, the user can enable Independent JTAG mode. In this mode you need to use separate cables on which Micro USB will access the PL (access TAP controller) and through the EMIO pins you access the PS (access DAP controller). But first you need to program the PL(through TAP) using Micro USB(preliminary enabling PJTAG from Zynq), and then you can debug ARM software through DAP controller.

Please read the JTAG (Slave Mode Boot) page 154 for more information.

Also read about ARM DAP and JTAG TAP controllers, Chapter27, page 717.

We recommend you to use the J15 header or Micro USB port to program the board. For J15 header, you can solder a 6-pin header or you can slightly pull up the pmod connector and this way you make room for the pin header.

The header was positioned in that place because there wasn't enough room on the board to place it on a more accessible space and we thought that most users do not use the additional header to program the board.

Best regards,

Ana-Maria

[mete]

Thanks Ana-Maria, great answer.