I have Xilinx Eval Board(SP605) with USB-UART bridge(SI CP210x). The board is connected to Win10 Computer USB port. The USB communication is failing intermittently when running tests. Observation so far,

  • Device is listed in Device Manager COM Port. Enable/Disable device in Device manager helps to recover
  • Device not listed in Device Manager COM Port. Disconnect/Reconnect USB cable on computer helps to recover
  • Power cycle SP605 helps to recover

Basically enumerating the device again helps to recover. Why is this happening? What/where is the problem.

Note: Test Application running on Win10 uses VCP driver for CP210X

Shall I use USB Switch to debug this problem? If driver is the problem, the second computer should be able to communicate to the device. I have to narrow down the problematic area. either SP605 eval board or driver in computer.


  • \$\begingroup\$ Show us the schematic and PCB layout of your CP201x part. \$\endgroup\$
    – brhans
    Jan 8, 2022 at 19:38

1 Answer 1


A very likely cause of intermittent USB connection is slight cable movement with dirty connector contacts.

To clean the USB connector contacts, first unplug everything: USB, power etc. Spray a little switch cleaner into the cable connector and plug/unplug it a few times. Leave it all unplugged for a couple of minutes for the cleaner to evaporate. Then try using it all.

Fault-finding starts by making sure of the basics: good clean connections, everything plugged in well, reliable power, nothing feels excessively hot to the touch, solder joints look good etc. Then you make your way down through increasingly complex possibilities.

  • \$\begingroup\$ @user12027865, can you give an update on what you found? \$\endgroup\$
    – TonyM
    Jan 20, 2022 at 2:57

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