PIC16F87 pins seem to be getting crossed over

[The Master]

The programmer is not attached. I have to take the chip out of the circuit to program it (Ive still not tried ICSP yet)

Ive tried adding the 3 lines from my last thread "CMCON = 7, CVRCON = 0, CCP1CON = 0". They have no effect.

I havn't done a schematic for this circuit but the input pin has a 100K pullup resistor and connects to an optoisolator that grounds it. The UART pins are connected to an RS485 chip along with portB.4 for driver/receiver control.

This circuit is actually for that time of year So far there has been a problem with every circuit ive made for it this year. Im still working on the others but i might have to make some other threads soon.

[rsocor01]

Hi,

Try a smaller pullup resistor, something like 4.7K. 100K pullup resistors might be too much. I hope this helps.

Robert

[The Master]

I dont think the pullup resistor is the problem. I want a fairly weak one to make it easy to ground. 100K should be more than enough to pull up any pin on a PIC. Ive used them many times before without a problem and there are 3 others on the same circuit working fine.