On Sun, Feb 19, 2006 at 01:59:48AM -0000, kerri wrote:
> Hi,
> 
> I have to questions about pic18f4550,
> 
> 1. I have noticed that if I touch the top of the ic with my finger
> the usb connection to my computer breaks. Is this normal?

Not likely... Usually that means a digital IO line has been left
floating somewhere. Check that every single digital input, including
ones going to the PC, is definitively held in a valid state.

One example of this would be IO lines on your PIC that aren't being
connected to them. Either make sure they are set as outputs, or tie them
to V+ or ground through a 10k resistor.

It may be the case that the USB link needs "steering" resistors attached
to it. I'm no expert on USB, but for instance the I2C protocol needs
resistors attached to the bus to establish valid signal levels. If you
don't do this, things *may* appear to work, but will be very flaky.

-- 
pete@petertodd.ca http://www.petertodd.ca
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist