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USB Power Surge Error PIC18F4550

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SamanthaL

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usb power surge error

Hello everyone!

I'm currently trying to interface a PIC18F4550 with a PC through a USB port and I'm getting an error that there is a power surge when I plug in the chip.

My schematic is as follows. I'm sorry I don't have a picture, but the connections are simple. The chip gets its power from the USB. The D+ and D- pins are connected directly to the USB. The Vusb pin has a 200nF capacitor connected to ground. I'm using a 20MHz oscillator with two capacitors connected to ground.

Is this power surge a hardware problem? Or is it something with the program? Have any of you had this problem before?

Thanks!
 

Your description sounds like a standard bus-powered circuit as expected, doesn't explain the problem of course. You didn't tell, in which phase of device connection/enumeration the power surgeis detected.

It would be also interesting if it even happens in reset state or without an operational firmware, not enabling the USB interface at all. If it's the case, than only a hardware defect or short circuit could explain the behaviour.

If the overcurrent is detected after regular device enumeration, an incorrect device descriptor may the trivial reason.
 

I'm not really sure when it takes place. I am an amateur with USB code. All I know is that it happens as soon as I plug in the USB port.

If it helps, the code I'm using is attached in a zip file. (Unzip to C drive. I'm using the HI-TECH compiler.) It's a sample I got from microchipc.com on emulating an RS-232 port through a USB port.

Thank you for your help.
 

The sample code should be O.K. I guess, it's rather a hardware problem.
 

    SamanthaL

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