Implementing a method with a Pin name as a parameter


A constant such as a Pin name cannot be passed to a sub routine or a function. This is a constraint of Great Cow BASIC.

A macro can be used to implement a method of passing a constant to reusable code section.

The example shown below implements a button press routine and takes an input port constant and prints the result on an LCD display.

Note: A macro will use more program memory as the macro will be compiled as inline code. Therefore, for every use of the macro will use additional program memory - the same amount of program memory for each call to the macro.

Demonstration Program:

    #chip 16F877a, 16
    #define Button PORTC.1    ' Switch on PIN 14 via 10K pullup resistor
    DIR Button In
    wait 1 sec

    'USART settings
    #define USART_BAUD_RATE 9600

    ;======== MAIN PROGRAM LOOP ================
    HSerPrint "Button Test"
    HSerPrintCRLF 2
       Test_button ( button )

    Macro Test_button (Button)
       if Button = ON then
          wait 10 ms          'debounce
          ButtonCount = 0

           Do While Button = On
               Wait 10 ms
               ButtonCount += 1

           if ButtonCount > 5  then
               if ButtonCount > 50 then   'Long push
                   hserprint "Long push"
               else                       'Short push
                   hserprint "Short push"
               end if
           end if
           wait 1 s
       end if
    End Macro

Also see Macros Overview