Spartan-6 LX9 MicroBoard

[JackBonn]

I am developing with both a Digilent 3AN development board as well as an LX9 Microboard.  I am running ISE 14.1 on Windows 7 (64 bit).

First what looks OK:  I can see "Digilent USB Device" under Universal Serial Bus controllers in the Device Manager.  I do have (many) "Microsoft Visual C++ 2008 Redistributable"(s) installed.  I can reliably load the FPGA from the SDK ("Xilinx Tools"..."Load FPGA").  I can "Initialize Chain" from Impact and it discovers one device, the xc6slx9.

I am having trouble loading images from the SDK on the LX9 board (the 3AN board is off).  For example, "Hello World" eventually works, but when downloading it pauses at 53% complete and a popup eventually appears stating:

  "Error stopping at main.  Reason: Target request filed: Target is not responding (timed out).  Continue?"

When I click on "yes", it eventually brings me to a breakpoint in main.  When I continue, it operates as expected, sending text to the USB-UART.

When I load something larger, like "Peripheral Tests", it waits (once again) at the 53% mark for a good while and then it puts up a popup:

  "Error stopping at main.  Reason: Target request failed: Reply contains invalid hex digit 116.  Continue?"
 
When I continue, it runs the program (successfully, all peripherals pass) and stops at a breakpoint in "exit()".

Any ideas?

[JackBonn]

Sorry, I now am plugging directly into the PC.

"Hello World" now works without timeout.

But when I run "Peripheral Tests", it still stops at the 53% mark for a good while and then it puts up the popup:

  "Error stopping at main.  Reason: Target request failed: Reply contains invalid hex digit 116.  Continue?"
 
Same result; when I continue, it runs the program without a breakpoint at main and stops at a breakpoint in "exit()".

I am confused.  Is the micro-USB to USB cable bad or is it the USB extender?

[JackBonn]

I unplugged the LX9 board from the USB port and used the "Platform Cable USB II", the Xilink USB to JTAG interface box.  I used the micro-USB port both for power as well as the USB-UART interface.  Everything now works as expected.

Next I will try direct connect on a different USB port to see if that helps. 

Anyone have any similar stories?  Any suggestions as to how to get the device to be able to work when plugged directly into a USB port?

[JBethurem · Accepted solution]

The onboard USB/JTAG interface only has a full-speed (10mbs) interface,  Thus its not quite fast enough
for real-time debugging with SDK.  It does function well for programming however.

If using SDK Debugger on this board, I recommend using the PC-USB.  

NOTE:  The Digilent HS-1 USB/JTAG cable has a hi-speed interface and works great!

[JackBonn]

I'm a little confused.  Is the full-speed (10 Mbps) interface you reference the USB side or the JTAG side?  I assume the the Xilinx PC-USB allows transfers faster than "full speed".

How does the performance of the HS-1 compare with the Xilinx adapter? Anyone have a JTAG interface that does USB 3.0 yet?

[JBethurem]

USB side.  The part on the LX9 MicroBoard is an Atmel ATMEGA part that has a Full Speed USB interface on one side, and used GPIO on the other to create the JTAG signals...      The HS-1 cable has the fastest interface going up to 480mbs.   I've done several tests and it has the fastest download speeds of any programming cable...    I have not seen anyone create a USB 3.0 cable yet...

If using this interface for programming only, direct programming the Flash using sfutil is very fast...