What is causing my problem?

[BobK]

Hello all!
It’s been a long time since I’ve posted here but I’ve still stayed in touch. I just made a project using a 16F87 and set 2
Outputs to 0 and I am getting voltage out of the pin that’s enough to turn the output transistors on. Can anybody give me a reason why a zero on a pin is not a zero? The original project I made back in 2005 was done with a 16F84a and is suppose to be pin compatible with the F87. The original project still works fine but I need another. Help, please!
Thank you, BobK

[Jerson]

Is it possible you did not set the TRISx register (where x is the port name) ? Perhaps the pin is an analog one by default and you haven't configured it for digital use?

these are what I can think of just now.

[BobK]

Thank you for the fast reply, Jerson.
I have 2 inputs on port A and the Tris A is =00000011 and the outputs are on port B and the Tris B is =00000000. I have the comparators disabled with CMCON = 7. Is there something missing here? Thank you!
BobK.

[tumbleweed]

... set outputs to 0 and I am getting voltage out of the pin that’s enough to turn the output transistors on.

What voltage are you measuring? Which PORTB pins are you using?

[Jerson]

Related to PORTB, I can see that only the ANSEL register is different.

I have some doubt if the ANSEL needs to be set to 0 on this chip.

If that does not help, then perhaps you can try by disconnecting the driven load and check if the outputs are following your code intent.

[tumbleweed]

PORTB has no analog functions on the 16F87.

Have you disabled the WDT?

[BobK]

No I did not disable the WDT. Is that necessary?