3 Replies Latest reply on Nov 19, 2018 6:57 PM by jgoeders

    Multiple JTAG/UART pods


      I'm trying to connect two Ultra96 boards to my Linux 16.04 workstation using the new JTAG/UART pods.

      Although both boards show up in "lsusb", they only ever appear as one entry to Vivado, so there is no way for me to individually program a desired board.  Other boards (such as PYNQ) correctly display 2 different cables in the Xilinx tools.  

      I should point out that I don't think there is any problem with either board.  If I just plug a single board in I can program it fine, after which I can unplug that board and plug the other board in, and again program fine.  The problem is getting that the JTAG/UART pods only show up as a single cable in the Xilinx tools.

      Is there a fix for this?



        • Are there any AVNET employees

          Are there any AVNET employees that can respond to this?  Is this a known issue with the JTAG/UART pods?

          • Two JTAG/UART pods on the same machine

            This has to do with the serial number of the FTDI device on the JTAG pod and the associated enumeration.  The JTAG/UART pods all show up with the same serial number.  The driver/OS can only associate one port with a given serial number.  Therefore, one machine will not see two JTAG/UART pods.

            The reason that the JTAG/UART pod serial number has been implemented in this way is that this guarantees that it will always show up as the same port.  In the past and on some machines, it would cause problems if the port number kept changing over time.  So in summary, this fixed serial number behavior cannot be modified without modifying the firmware on the JTAG pod.  And currently Avnet cannot make that firmware public.

            • Thanks, that's what I

              Thanks, that's what I suspected.  I would have rather this had been implemented with varying serial numbers, as I have experienced with other FPGA development boards.  The choice to use the same serial for each board makes it impossible to perform experiments on multiple boards simultaneously without requiring one computer per board (unless there is some workaround).

              Nevertheless, I really appreciate the clear and quick answer.