Strange that you should mention this now -- I am having a very similar problem with the external interrupt, using the same bondout chip. Although I can't offer help with your problem, I will tell you about mine, which may help jog someone's memory of how they overcame this problem. I am _not_ using weak pullups, and trying to use RB0 as an external interrupt. The input is an analogue level so I am relying on the supposed schmidt trigger action of RB0 when used as an input. Well the funny thing is that when the input voltage is between the trip points of the schmidt trigger, the interrupt routine is unable to clear the interrupt flag in intcon. I can see this when stepping through the bcf intcon,intf instruction. (Actually, sometimes it clears, but mostly it does not. I am monitoring the input on an oscilloscope and I'm fairly sure there are no spikes -- everything is dead quiet when I pause the emulation). Naturally, this causes the interrupt routine to retain control forever after. Dammit, I am going to have to insert an external schmidt trigger! Regards, SJH Canberra, Australia > From: Bernie Gordon > > > >I am having difficulty emulating with a PIC16C74. I am using a RICE16 > emulator, and looking for a change in PORTB. I have set INTCON to a hex C8, > and PB2 thru PB7 are setup for input, with weak pullups. When I ground PB4, > the emulator processes the interrupt, but performing a read on PORTB does > not enable me to clear bit 0 of INTCON. Can anyone help me with this problem? > > > >If the input is transient, and returns to '1' immediately during the > interrupt there is no problem, but if the input remains at '0', difficulties > ensue.