The function eliminates the influence of contact flickering upon pressing a button (debouncing). The Button pin is tested just after the function call and then again after the debouncing period has expired. If the pin was in the active state in both cases then the function returns 255 (true).

• port: button port address
• pin: button pin
• time: debouncing period in milliseconds
• active_state: determines what is considered as active state. Valid values: 0 (logical zero) and 1 (logical one)

• 255 if the pin was in the active state for given period.
• 0 otherwise

Nothing.

program Button_Test;

var oldstate : bit;

begin
  oldstate := 0;
  ADPCFG := 0xFFFF;                             // initialize AN pins as digital
  TRISD := 0xFFFF;                              // initialize PORTD as input
  TRISB := 0x0000;                              // initialize PORTB as output

  while TRUE do
    begin
      if (Button(PORTD, 0, 1, 1)) then                     // detect logical one on RB0 pin
        oldstate := 1;
      if (oldstate and Button(PORTD, 0, 1, 0)) then
        begin                                              // detect one-to-zero transition on RB0 pin
          LATB := not LATB;
          oldstate := 0;
        end;
    end;                                                   // endless loop
end.

None.