Good day to all. An older project of mine needs to have a card re-designed because the original chip on that board is no longer available. Its a 74c945 LCD counter and it seems to be no longer available. I have a standard interface and software for driving LCD glass using shift registers. My problem is that I have to emulate the original part - this requires quick recognition of 3 signal lines: clock, latch, reset. The pulses driving those lines are short - on the order of 40 uS or so. These short pulses mean that it will be a pain to rely upon polled reads of the inputs. I could do it, but it would mean interspersing the port reads every couple of dozen instructions in the code. I'd like to use interrupts - but without adding external gates. I can use 2 interrupt sources easily - INTF and T0IF. But I need 3 inputs. I have always avoided using port change interrupts while my code is running because of the missed interrupts that have always been a problem in past. But I'm looking at the current data sheet for the 12c671 and I don't see any problems with the 'interrupt on port change' mentioned. Does anyone know if the previous problems with that have been fixed? Does anyone use the port change interrupt while they are changing the other bits on that port? Or is the port change interrupt still only useful for waking the chip from sleep? Many thanks! dwayne Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 16 years of Engineering Innovation (1984 - 2000) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.