Raymond Choat wrote:
> Yep I would of burned something up doing it that way. Attached  is my
> corrected version. Let me see if I have this right. I connected the switches
> between the two resistors (pullup and zap protection). So does this mean the
> line from pic1 and the button both are held high and when I ground either
> one the line to pic2 goes low which activates part of the program? Now the
> line from pic1 has zap protection but the buttons do not. I have used
> buttons before without zap protection without trouble. Do I need the zap
> protection on the switches and if I do, will I just put 1k resistors  in
> series with the buttons? Normally when I use the buttons (to test board) the
> pic1 portB output would be high (not activating anything) or not connected
> at all.

Whether you need ZAP protection on the switches depends on the type of
switch you are using. For example, if these are metal snap dome type
switches that are uncovered, then a finger charged with static can
discharge into the PIC2 inputs. If these are insulated switches, then
zap protection is (probably) not required. To be on the SAFE side (if
you are in doubt), add resistors (~1K) in the wires connecting going to
the PIC2.

If you add 1K resistors in series with the buttons, and the PIC1 is
driving high, then the voltage at the PIC2 is ~2.5V (which will NOT
provide a valid signal).

David W. Gulley
Destiny Designs

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