eskull

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About eskull

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  1. Hello, We have a Xilinx VC709 board. We had it plugged into PCIe slot on one computer, and then had the Digilent USB/JTAG interface connected to a second computer to remotely re-program the VC709 BPI flash. This worked fine for a day or two, and then the interface stopped working (Digilent no longer appeared in Vivado HWM, nor in host Win10 Device Man). We ordered a new SMT2 and swapped out the failed interface. The VC709 programmer now works correctly. However, to hopefully prevent this happening again (we must have had a ground loop...) we would like to purchase an in-line USB isolator. One we are considering does not drive the 5V line on the USB cable, so that line will be 0V at the SMT2 UBS connector input. My question - by what means does the SMT2 sense connection to Vivado HWM? Is it via detection of the USB 5V line? In other words, if the USB cable 5Vpin is 0V, will the SMT2 still enumerate to the host (i.e., operate correctly)? Thank you.
  2. eskull

    JTAG STM1 stopped working

    Re, ground loops, what I meant by this, the SMT1 UBS port is connected (via USB cable) to an external computer potentially on a separate ground plane than what the VC709/SMT1 is connected to. This could cause a current to flow over the USB cable ground via the dissimilar ground planes. Something we hadn't considered before making this connection. Thank you again for your time and help.
  3. eskull

    JTAG STM1 stopped working

    Will give it a try. However, I do not understand what exactly you meant in the above response: “presuming you have set SW11 to101” Do you mean, I need to set SW11 to 101 in order to execute the linked prog app you sent ? Note that the VC709 UG states to set to 010 (position 3, 4, 5) for BPI access, which is how we want to operate. Thank you for the help.
  4. eskull

    JTAG STM1 stopped working

    Hello, We have a Xilinx VC709 FPGA board (Virtex 7), with a JTAG-STM1 interface. The JTAG programmer no longer shows up in either Windows 10 Device Manager, nor does it show up in Vivado (2018.2) Hardware Manager. A second VC709 works correctly so it doesn't appear to be driver/SW issue. Probed the TCK, TMS, TDI pins - all are pulled high (3.3V) showing no activity. We had this VC709 installed in to a PCIe slot on a PC, with the JTAG-USB cable connected between the VC709 and a laptop. Is there a clue in this setup, as to how the STM1 might have failed (e.g., ground loop - what would be most likely failure point on STM1)? The VC709 otherwise appears to work fine - there is a PCIe design in the BPI Flash that loads on power-up and links to host PCIe, as well as flashing status LED's as expected. We just can no longer reprogram FPGA/FLASH. Are there any probe points on the STM1 we can check (with DSO) to isolate problem? Thank you.