10-Second Counter

I have made a 10-Second Counter by using a PIC16F627a and a CD4543 BCD to 7-Segment decoder. This circuit and source code are just a demonstration of using MCU to drive an LED 7-Segment Display via CD4543. The 7-Segment displays from 0 to 9 and the number will roll over to 0 again. The interval between change is 1 second. So, this circuit counts 10 seconds between the roll over. I use TIMER1 module and 32.768KHz crystal to make 1 second timebase (see Clock with 32.768KHz Crystal for more info ).

The schematic of the 10-Second counter

Project setting of MikroC for using internal oscillator of the PIC16f627a.


The firmware is written in MikroC and you can find it below.

//PIC16F627A
//4MHz Internal OSC
// One Digit Counter
// 06/11/2008
//Punkky
unsigned short counter;
unsigned short tick;
void interrupt ()
{

        PIR1.TMR1IF = 0;        // clears TMR1IF
        TMR1H = 0x80;
        tick = 1;
}

void main(){
        CMCON = 0x07;   //Digital I/O for PORTA
  TRISA = 0x00;
  PORTA = 0x00;
  TRISB = 0x00;
  PORTB = 0x00; 
  T1CON = 0x0F; 
         
  // Prescaler 1:1   external clock 
  PIE1.TMR1IE = 1;  // enable interupt to start the clock 
  INTCON = 0xC0;   // Set GIE, PEIE 
  TMR1L = 0x00; 
  TMR1H = 0x80; 
  PCON.OSCF = 1; //Internal Clock 4MHz
  //PCON.OSCF = 0; //Internal Clock 48KHz doesn't work well
  counter = 0;
  tick = 0;
  PORTA.F0 = 1; // Enable 4345 BCD to 7-Segment
  while(1){
    if(tick){
       tick = 0;
       counter++;
       PORTB = counter;
       if(counter>9){
       counter = 0;
    }
   }
  }
}