Vivado 2020 hardware server not finding my CMOD A7 anymore

[Nefastor]

Hi. I've just installed Vivado 2020.1 on my Windows 10 machine for the purpose of programming a CMOD A7 module. Which it managed to do, a couple of times : after generating a bitstream I'd open the Hardware Manager and then hit Open Target, select Auto Connect, and within five second it would find the board and let me program it. Ten minutes later, Vivado started randomly losing connection to the module. And then I wasn't able to connect to it anymore. When using Auto Connect, it just sits there "scanning" or something, and nothing ever happens.

How do I fix this ? I can't seem to be able to kill and restart the HW server, and it doesn't seem like there's a firewall issue or some other BS Windows pulled behind my back.

As it stands, my module is unusable and I've wasted a whole day installing tools that don't work reliably.

[Nefastor]

After experimenting with a second PC and different USB ports, I still had the same issue. That led me to believe this was a power issue, and I was right. It seems the CMOD A7-35T draws too much power from the USB port. Powering it with a dedicated 5V PSU almost solved the issue. The module no longer drops in and out of the OS, and it can be programmed reliably... most of the time. For some reason the HW server still loses track of it, closes it after a while for no discernible reason, however this is easily fixed by asking Vivado to re-open the target.

I don't know, this isn't a great look for Digilent and Xilinx when a cheap Chinese Arduino knock-off is more reliable than a 100 € FPGA module... you might want to do something about it.

[xc6lx45]

Hi,

please search the forum, it's fairly common and frequently resolved. Use a different cable, use a different computer (there is a high number of bad quality USB cables on the market; there are many unreliable PC ports e.g. because of bad polyfuses that have once tripped and never recover completely).

You may have a bad module and there exists a newer hardware revision with improved decoupling caps but most likely the easiest way ahead for you is to get a quality cable and rule out issues with the USB port on the PC side.