"The semaphore timeout period has expired" error for USB connection

Solution 1:

Okay, I am now connecting without the semaphore timeout problem.

If anyone reading ever encounters the same thing, I hope that this procedure works for you; but no promises; hey, it's windows.

In my case this was Windows 7

I got a little hint from This page on eHow; not sure if that might help anyone or not.

So anyway, this was the simple twenty three step procedure that worked for me

• Click on start button

• Choose Control Panel

• From Control Panel, choose Device Manger

• From Device Manager, choose Universal Serial Bus Controllers

• From Universal Serial Bus Controllers, click the little sideways triangle

• I cannot predict what you'll see on your computer, but on mine I get a long drop-down list

• Begin the investigation to figure out which one of these members of this list is the culprit...

  • On each member of the drop-down list, right-click on the name

  • A list will open, choose Properties

  • Guesswork time: using the various tabs near the top of the resulting window which opens, make a guess if this is the USB adapter driver which is choking your stuff with semaphore timeouts

• Once you have made the proper guess, then close the USB Root Hub Properties window (but leave the Device Manager window open).

• Physically disonnect anything and everything from that USB hub.

• Unplug it.

• Return your mouse pointer to that USB Root Hub in the list which you identified earlier.

• Right click again

• Choose Uninstall

• Let Windows do its thing

• Wait a little while

• Power Down the whole computer if you have the time; some say this is required. I think I got away without it.

• Plug the USB hub back into a USB connector on the PC

• If the list in the device manager blinks and does a few flash-bulbs, it's okay.

• Plug the BlueTooth connector back into the USB hub

• Let windows do its thing some more

• Within two minutes, I had a working COM port again, no semaphore timeouts.

Hope it works for anyone else who may be having a similar problem.

Solution 2:

This error could also appear if you are having network latency or internet or local network problems. Bridged connections that have a failing counterpart may be the culprit as well.

Solution 3:

I had this problem as well on two different Windows computers when communicating with a Arduino Leonardo. The reliable solution was:

• Find the COM port in device manager and open the device properties.
• Open the "Port Settings" tab, and click the advanced button.
• There, uncheck the box "Use FIFO buffers (required 16550 compatible UART), and press OK.

Unfortunately, I don't know what this feature does, or how it affects this issue. After several PC restarts and a dozen device connection cycles, this is the only thing that reliably fixed the issue.