[sdiy] PICs sharing pins and clock

[Scott Gravenhorst]

You may want to connect these pins through a resistor.  If you have errors in
your programs while developing, you can inadvertently set both PIC's pins to
outputs.  If that happens and one goes low while the other goes high, you can
damage one or both.  To avoid such damage, connect the pins through a resistor.
 The docs tell you the range of resistance that is acceptable, but I believe
10K will work and will prevent excessive current.  Other than that, program
timing could be interesting.

fmg <eqys at iposadas.com.ar> wrote:
>To the pics gurus,
>
>Is this possible?  I mean, can two (or more) PICs work together, one
>with one of its pins working as output and connected to a second one
>configured as input, both sharing a common external clock?
>
>Example (for better clarity): pin RB0 (from PIC #1) as output and directly
>connected to pin RA0 (from PIC #2) as input...
>
>instruc.
> cycle       pic #1                        pic #2
>------------------------------------------------------      (-x- = don't care)
>  Tn           -x-                           -x-
> Tn+1      incf   portB,1   -------->   btfsc   portA,0
> Tn+2          -x-                      goto XX
> Tn+3          -x-                      goto YY
>
>...will pic #2 go to XX if RB0 from pic #1 changes from 0x00 to 0x01 ?
>
>The 16f84a's datasheet is a bit confusing (or I'm not interpreting it
>correctly). I'm also not sure if this is the correct place to ask (even
>if this is for a synth project)
>
>Any light would be appreciated, TIA
>
>
>Fabio
>(listening R van Gaal's Closer to the Truth)
>.
>
>PS (...wich is a good thing to listen to at 03:30 am)
>

---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.