Re: pic output port

Hi Tony,

Tony wrote:
> i want to turn on an npn switching transistor from an output port of a pic
> 16F84. my question is do i need a resistor between the npns' base and the
> port of the pic or can i turn it on directly?

In addition to what the other posters said, you _can_ omit the base
resistor if (and only if) you configure the port as having
"weak pullups" and switch the port with the TRIS bit.

TRIS bit set means input = pullup to Vcc = NPN will be on
TRIS bit clear AND PORT bit clear means "output low", NPN will be off.

But take care you always have a 0 in the corresponding PORT output latch!

HTH
Wolfgang