I am having a problem with a 16F628 driving an LCD.

The program uses portB driving a 16207H LCD panel using a 4 bit interface.
The same code works perfectly in a 16C84 in the same circuit.

A program dump from the 628 chip shows correct code in the chip.  Several
different chips all show the same symptoms.

I have looked at the signals with a scope and find that the RB7 pin (busy
flag from the LCD) is oscillating 4 MHZ at 1 volt with a sawtooth waveformm
whether connected to the LCD or not.

I've tried pullups, pulldowns, capacitor filtering all with no effect.

A test using the port as output only (a simple walking 1 output program)
works fine.

Hope someone can point me in the right direction.

Regards,
Doug Hemingway

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics