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

Function eliminates the influence of contact flickering upon pressing a button (debouncing).

Parameter port specifies the PIN register of the desired port; parameter pin is the pin number on designated port and goes from 0..7; parameter time is a debounce period in milliseconds; parameter active_state can be either 0 or 1, and it determines if the button is active upon logical zero or logical one.

Button pin must be configured as input.

On every PB0 one-to-zero transition PORTC is inverted :

bit oldstate;                       // Old state flag

void main() {

  DDB0_bit = 0;                     // Set PB0 pin as input

  DDRC  = 0xFF;                     // Configure PORTC as output
  PORTC = 0xAA;                     // Initial PORTC value
  
  oldstate = 0;
  
  do {
    if (Button(&PINB, 0, 1, 1)) {   // Detect logical one
      oldstate = 1;                 // Update flag
    }
    if (oldstate && Button(&PINB, 0, 1, 0)) { // Detect one-to-zero transition
      PORTC = ~PORTC;               // Invert PORTC
      oldstate = 0;                 // Update flag
    }
  } while(1);                       // Endless loop
}