interrupt handling faster than if's?

[keithdoxey]

Thinking about this further, and assuming you are only using the pin values to send to the other end then

TRANSMITTER

PORTSTATE var Byte
LASTSTATE var Byte


Main:
     PORTSTATE= PORTA & $0F ' mask Port A to retrieve lower 4 pins
     If PORTSTATE <> LASTSTATE then     ' something has changed
            LASTSTATE = PORTSTATE
            Hserout [PORTSTATE]
     Endif
     Pause 10
     Goto Main

RECEIVER

Main:
      Hserin 20,Main, [PortState]
      PortState = PortState ^ $0F  ' EOR to invert pin states (omit this line if you want normal state)
      PORTA = Portstate   ' Set the pins
      Goto Main

That would save loads of program space provided you did not need individual pin states for any other purpose.

Dont forget the set the TRISA registers to configure pins as Inputs and outputs.

NB: There might be slight errors above as I rarely get it right first time!!!!

[mbw123]

Thanks for the many responses. I am going to eventually hook it up to a radio link so I will probably need the Pre and Synch values. Using your code previously posted, I should be able to just add those variables in, right? Thanks again (I will test the code right now)...

-Mike

[mbw123]

One last thing. Will the code (your most recent post before this one) work when two or more buttons are pressed at the same time? Thank you for the help.

-Mike

[keithdoxey]

One last thing. Will the code (your most recent post before this one) work when two or more buttons are pressed at the same time? Thank you for the help.

-Mike

Hi Mike, multiple keypresses shouldnt be a problem as it takes the value of all switches as a 4 bit binary value eg 0110 and sends that to the distant end where you write 1001 (or 0110 if you dont invert) to the output port.

LASTPORT gets set as 0110 ( or 6 if you prefer) and the next time it looks at the port if the value is any different the new value will be sent and stored.

It doesnt matter whether it has changed to 0100, 0111, 1010 etc because all of them are different to 0110 and the entire port value will be replicated at the distand end with just a single command string.