Re: Is it safe to parallel PIC chip outputs

On Apr 8, 4:18 pm, Randy Day <randy....@xxxxxxxx> wrote:
meld_...@xxxxxxxxx wrote:

[snip]

I need a source output. Basically I want to power an op amp and some
sensors, so I can shut them down when the PIC is in sleep mode. Is
there a drawback to running the output pins in parallel, that
justifies the additional components for an external transistor?

Unless you're limiting yourself to SETF
and CLRF statements, if you happen to
leave one output 0 when all others are 1.
say goodbye to your micro.

How many chips are you prepared to lose
during the debugging process?

"Oops, that was supposed to be MOVF PORTB, W
not MOVWF PORTB", as a wisp of smoke rises
from your circuit...

Hi, Randy. Assuming the OP is paralleling outputs to drive a
resistive load, he could use current limiting resistors at each output
to help during the debugging process, like this (view in fixed font or
M$ Notepad):

|
| .------. .-------.
| | | | | ___
| | o--. | o-|___|---.
| | | | | | | 270 | |
| | | | ___ |/ | | ___ | |/
| | o--o-|___|--| = | o-|___|---o-|
| | PIC | | 100 |> | PIC | 270 | |>
| | | | | | | ___ | |
| | o--' === | o-|___|---' ===
| | | GND | | 270 GND
| | | | |
| '------' '-------'
|
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

You have a very good point -- the OP should do everything he can to
protect his development system from himself. ;-)

Cheers
Chris

.