> I wonder if anyone could adivse me. I made a PIC16F84 circuit using all
13
> I/O pins to drive 13 LEDs, but the LED connected to RA4 doesn't light up.
It
> appears that the pin does provide a signal, though. When I read up some
more
> in the PIC16F84 datasheet, I came accross a paragraph which said that all
RA
> pins are CMOS drivers, except RA4 which is an "open-drain" output. Is
this
> why it can't deliver current?
Exactly. It only sinks current. Connect all you LEDs and resistors between
+%V and the pins, invert what you wrte to the orts and it should work.
Wouter