/* Toggle an LED with a Push Button Switch 
PIC16F877A* 4MHz, MCLR Enabled, PWRT Enabled, WDT OFF */
// Define the LED * RD0 and push button switch * RC0
sbit LED at RD0_bit;  //RD0_bit == PORTD.B0
sbit Switch at RC0_bit; //RC0_bit == PORTC.B0
// Macros for Button() function
#define Switch_Pin 0  // BUTTON at pin 0 of PORTC
#define Switch_Port PORTC//BUTTON at  PORTC
#define Debounce_Time 20  // Switch Debounce time 20ms
void main() 
{
TRISD = 0;   // PORTD All Outputs 
TRISC = 0b11111111;  // PORTC All Inputs 
LED = 0;    // Initial condition
    do {
              if (Button(&Switch_Port, Switch_Pin, Debounce_Time, 0)) 
                 {
                   if (!Switch) // Check the button press again after the debounce time
                     {      
                       LED = ~LED;
                      }
                   while (!Switch);  // Wait until the button is released
                 }
         } while(1);    // Infinite Loop
}

bit oldstate;                                    // Old state flag
void main() {
  TRISC0_bit = 1;                          // set RC0 pin as input
 
 TRISD0_bit = 0;                          // Configure as output
 PORTD = 0;                                 // Initial PORTD value
 oldstate = 0;
 
 do {
        if (Button(&PORTC, 0, 10, 1))     // Detect logical one = BUTTON NOT PRESSED ?  
         {      
            oldstate = 1;                              //  YES > Update flag T0 1
          }
       if (oldstate && Button(&PORTC, 0, 1, 0)) // Detect one-to-zero transition 
          {   
            PORTD = ~PORTD;                              //YES ,  Invert PORTD
             oldstate = 0;                                           // Update flag TO 0 AGAIN 
           }
      } while(1);                                    // Endless loop
}

  TRISC.B0 = 1;                                // set RC0 pin as input
  TRISD = 0x00;                                  // Configure PORTD as output
  PORTD = 0x00;                                  // Initial PORTC value
  oldstate = 0;
  do {
    if (SWITCH_OFF) oldstate = 1; // Detect logical one , Update flag
    if (oldstate && SWITCH_ON) {   // Detect one-to-zero transition
      LED= ~LED;                            // Invert OUTPUT
      oldstate = 0;                              // Update flag
    }
  } while(1);                                    // Endless loop
}