Quote Originally Posted by Darrel Taylor View Post
If you are using an external power supply, you should not connect the +5 volts to Pin 1 of the USB connector.
Not sure if you meant that in post #1 USB connections.

If you do, it will cause an over current condition, and the USB port will shut-down.

The capacitor should be at least .22uF (220nF).
It may still work with 100nF, but it may also be unstable.
I have a schematic that is surely a working system where I can see all the same things (100nF, 22ohm). However I will change the Vusb=100nF to bigger one day, soon... just to be more on the safe side...

The +5V is not connected to USB port, instead USB-connector.1 is connected to PIC portB.5 (pin 38) so the software can detect when the USB cable is connected. There could also perhaps be an USB interrupt possibility, but I thought this would be simpler looked from the program side, on change interrupt or perhaps just polling, ... let's see said the blind man ...