Interfaceing another PIC? Replacing a existing Digital chip with My PIC

[wdmagic]

chirpy, thats a maximum rating, in the notes on the side it states its using a 5volt logic supply.
its like most PIC's have a 5.5v max, but we never run them at that. I can only assume they designed it that way to be able to use 6volt external/isolated supplys , the internal componets probobly regulate the voltage a bit or have isolation parts for the interfacing.

NOTE: if you look on page 4 it says normal range is 5 volts and max is 5.5, im not sure why they say 7 on page 1 as a max.

[HenrikOlsson]

Yes, the 16MHz x-tal is liekly driving the main processor but what I mean with clock frequency in this context is the frequency of the clock that drives that communication between the main board and the display board. If you look at the datasheet for the LED driver chip you'll see that it's basically a shift register. It shifts data in on pin 2 one bit at a time each time there's a rising edge on pin 3. What you need to know is the frequency of that clock signal and the frequency of the latch signal - which can be thought of as the "frame rate" of the display.

Put a scope probe on the latch signal (pin 4 on the A6276) and another probe on the Clock signal (pin 3 on the A6276) and see if you can get a stable trace on the scope (I'm guessing that it's an anlog scope and not a digital sampling scope). That will tell you how often the display is refreshed and the frequency of the clock signal.

It's possible that the display is only refreshed when something actually changes so you may need to push some buttons or whatever on that main board - what ever that is.

/Henrik.