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

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).

Parameters :

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

Button_Pin variable must be defined before using this function.

P2 is inverted on every P0.B0 one-to-zero transition :

// Button connections
sbit Button_Pin at P0_0_bit;        // Declare Button_Pin. It will be used by Button Library.
// End Button connections

bit oldstate;                       // Old state flag

void main() {

  P0 = 255;                         // Configure PORT0 as input
  P2 = 0xAA;                        // Initial PORT2 value
  oldstate = 0;
  
  do {
    if (Button(1, 1))               // Detect logical one
      oldstate = 1;                 // Update flag
    if (oldstate && Button(1, 0)) { // Detect one-to-zero transition
      P2 = ~P2;                     // Invert PORT2
      oldstate = 0;                 // Update flag
      }
  } while(1);                       // Endless loop
}