4-Digit 7-segmant display counter using PIC16F84A and CCS PIC C compiler

Interface PIC16F84A with 7-segmant display

This topic shows how to build a digital counter that counts from 0 to 9999 using PIC16F84A microcontroller and CCS PIC C compiler. The 4-digit 7-segment display uses multiplexing technique which means all the data lines from a to g are connected together for all the four digits. We will see circuit and code for both types of the 7-segment display common anode and common cathode.
The following video shows a hardware circuit of the digital counter:

 

Interface PIC16F84A with common anode 7-segmant display:
In common anode 7-segment display type all the 7 LED's anodes are connected together.
Interfacing PIC16F84A with common anode 7-segmant display (digital counter circuit) circuit schematic is below.

If the button which is connected to RB7 pressed the displayed number will increment by 1.
4-Digit common anode 7-segment display counter interfacing with PIC16F84A CCS C code:

// 4-Digit digital counter using PIC16F84A
// http://ccspicc.blogspot.com/
// electronnote@gmail.com

#include <16F84A.h>
#fuses HS,NOWDT,PUT,NOPROTECT
#use delay(crystal=8000000)

short s;   // Used to know button position
unsigned int digit, digit1, digit10, digit100,digit1000;
unsigned long i;
unsigned int seg(unsigned int num) {
  switch (num) {
    case 0 : return 0xC0;
    case 1 : return 0xF9;
    case 2 : return 0xA4;
    case 3 : return 0xB0;
    case 4 : return 0x99;
    case 5 : return 0x92;
    case 6 : return 0x82;
    case 7 : return 0xF8;
    case 8 : return 0x80;
    case 9 : return 0x90;
   }
}
void main() {
  while(TRUE) {
   if(input(PIN_B7) == 1)
     s = 1;
   if(s == 1) {
     if(input(PIN_B7) == 0) {
       s = 0;
       i++;
       if(i > 9999)
         i = 0;
     }
   }
   digit = i % 10;
   digit1 = seg(digit);
   output_a(0x0F);             // Turn off all displays
   output_b(digit1);           // Send ones digit
   output_a(0x07);             // Turn on display for ones
   delay_ms(5);
   digit = (i / 10) % 10;
   digit10 = seg(digit);
   output_a(0x0F);             // Turn off all displays
   output_b(digit10);          // Send tens digit
   output_a(0x0B);             // Turn on display for tens
   delay_ms(5);
   digit = (i / 100) % 10;
   digit100 = seg(digit);
   output_a(0x0F);             // Turn off all displays
   output_b(digit100);         // Send hundreds digit
   output_a(0x0D);             // Turn on display for hundreds
   delay_ms(5);
   digit = (i / 1000) % 10;
   digit1000 = seg(digit);
   output_a(0x0F);             // Turn off all displays
   output_b(digit1000);        // Send thousands digit
   output_a(0x0E);             // Turn on display for thousands
   delay_ms(5);
   }
}

Interface PIC16F84A with common cathode 7-segmant display:
In common cathode 7-segment display type all the 7 LED's cathodes are connected together.
The following circuit schematic is for 4-digit digital counter counts from 0 to 9999, the number is incremented when button is pressed.

 

 4-Digit common cathode 7-segment display counter interfacing with PIC16F84A CCS C code:

// 4-Digit digital counter using PIC16F84A
// Common cathode 7-segment display
// http://ccspicc.blogspot.com/
// electronnote@gmail.com

#include <16F84A.h>
#fuses HS,NOWDT,PUT,NOPROTECT
#use delay(crystal=8000000)

short s;   // Used to know button position
unsigned int digit, digit1, digit10, digit100,digit1000;
unsigned long i;
unsigned int seg(unsigned int num) {
  switch (num) {
    case 0 : return 0x3F;
    case 1 : return 0x06;
    case 2 : return 0x5B;
    case 3 : return 0x4F;
    case 4 : return 0x66;
    case 5 : return 0x6D;
    case 6 : return 0x7D;
    case 7 : return 0x07;
    case 8 : return 0x7F;
    case 9 : return 0x6F;
   }
}
void main() {
  while(TRUE) {
   if(input(PIN_B7) == 1)
     s = 1;
   if(s == 1) {
     if(input(PIN_B7) == 0) {
       s = 0;
       i++;
       if(i > 9999)
         i = 0;
     }
   }
   digit = i % 10;
   digit1 = seg(digit);
   output_a(0);             // Turn off all displays
   output_b(digit1);           // Send ones digit
   output_a(8);             // Turn on display for ones
   delay_ms(5);
   digit = (i / 10) % 10;
   digit10 = seg(digit);
   output_a(0);             // Turn off all displays
   output_b(digit10);          // Send tens digit
   output_a(4);             // Turn on display for tens
   delay_ms(5);
   digit = (i / 100) % 10;
   digit100 = seg(digit);
   output_a(0);             // Turn off all displays
   output_b(digit100);         // Send hundreds digit
   output_a(2);             // Turn on display for hundreds
   delay_ms(5);
   digit = (i / 1000) % 10;
   digit1000 = seg(digit);
   output_a(0);             // Turn off all displays
   output_b(digit1000);        // Send thousands digit
   output_a(1);             // Turn on display for thousands
   delay_ms(5);
   }
}