16f628 A4 output

[Don P]

Look at the internal equivalent circuit of a 2003 . . . to give typically 1.6v. Since Vih for A4 is typically 4v, as PCM Programmer says, you _will_ see the RMW problem.

Thanks both! I dropped the pullup below 800 & it now works fine. I'll have to read up more on the RMW problem, too.
Regards,
Don

[abdullah]

I had the same problem a couple of times before mainly when I try to blink aled on that pin .I think pin works like a current sink since it works fine when used as negatif voltage reference