When usb attached to FRDM board, strange issue when applying 3.3v to coin cell location

[steve_fae]

When I attach an external power supply of 3.3v to TP8, and also have USB connection to PC for debug, the glide point on my laptop starts to drag and is difficult to use.  If I turn off the external 3.3V and just let USB power the FRDM board, it works fine.  Could USB power from my PC be effected in some strange way?

[Paul_Tian]

Hi, Steven

I checked your operation on my freedom board(external 3.3V to TP8). Following is my testing result.

In CodeWarrior, I test a new project, and everything works well in debug mode.

In IAR, I test USB device demo project, and everything works well in debug mode. PC can detect freedom board as a USB device.

I think your problem might caused by your PC side. You can restart your PC and reinstall the driver then try again.

Hope my reply can help you.

Best Regards

Paul

[steve_fae]

Thanks Paul. I might agree that its inherent to my PC.

Steven Cohen

[bobpaddock]

"I might agree that its inherent to my PC. "

Two things to check:

1) Make sure there are no duplicate USB PID/VID pairs between your FRDM board and something else on your PC.

USBDeView is a good tool for this: View any installed/connected USB device on your system

2) Look at Device Manager and see if you have any USB ports what have a different hub controller.

Try the different port.  I once ran into a case where an Atmel ARM part would work just fine with Intel Hubs on the Mother Board, but would not work correctly with NEC Hub on the same Mother Board.