USB 18F2550 Problem

[mackrackit]

The problem was fixed by adding this to the configs
_XINST_OFF_4L
And I made sure the internal regulator is on to feed the internal USB pullups.

Power wise I am running the chip at 3.3 so the only thing I have connected to VUSB is the capacitor to VSS.

Now I do have some more reading to do as there is mention in the data sheet about VDD has to be higher than VUSB.
But it is working for now. Long term ????

Newbies---- IMHO Compared to two or three here we all are some newbie. But we can learn from anyone if we care to listen.

[rsocor01]

Well, I have a different setup. I disabled the internal regulator and fed 3.3V directly to VUSB. I assume the internal pullup resistors are enabled because my setup works fine. Otherwise, if they were disabled the USB interface wouldn't work because I believe the pullups are a requirement for USB.

I think the internal regulator function is to convert Vcc=5V to 3.3V which is necessary by the USB module. But, since you already have the 3.3V, then why the need to use the internal regulator?

Now I do have some more reading to do as there is mention in the data sheet about VDD has to be higher than VUSB.
But it is working for now. Long term ????

I have been through that pain already . Take a look at post# 4 in the following link.

http://www.microchip.com/forums/tm.a...&high=rsocor01

Please, let me know if you find out something else about this whole thing.

Robert