4 Digit Seven Segment Up Counter Circuit - 16F628 ~ Scorpionz - Electronic Circuits and Microcontroller Projects

In the past I posted a counter and timer circuit and it is used two seven segment displays to display number and it can only count 0-99. you can see it from here. This circuit was developed version of it.

This project shows cheap and accurate up counter and it can count up to 9999 and then it will start from 0. For this circuit i used PIC16F628A micro-controller and four common cathode seven segment displays. Any 7-Segment displays will work in this circuit. You need to identify the pin-out of any display you use. In Proteus schematic i used NOT gate for reduce CPU usage while simulating and you need to replace that NOT gate with NPN transistors such as BC547 and do not connect transistor's base directly with PORTA (A0-A3). Put a 1k-10k resistor for base of each transistor.

Schematic diagram of 4 digit up counter

Operation of Circuit

To start counting simply press the 'Count' button and every time you pressed that button the number will increase one by one and displayed on the seven segment displays. if you need to automatic counting, it is also possible to connect this pin with pulse generator.
Pressed 'Clear' button to clear the display and start from zero.
'Reset' button is optional and you can omitted it. but you must add pull-up resistor. otherwise device will reset continuously. 'Reset' button is useful when the circuit was stuck or not responded.

The main problem of counter circuit was contact bounce. The contact bounce is a common problem with mechanical switches. When the contacts strike together, their momentum and elasticity act together to cause bounce. The result is a rapidly pulsed electrical current instead of a clean transition from zero to full current. It mostly occurs due to vibrations, slight rough spots and dirt between contacts. This effect is usually unnoticeable when using these components in everyday life because the bounce happens too fast to affect most equipment. However, it causes problems in some analog and logic circuits that respond fast enough to misinterpret on/off pulses as a data stream. Anyway, the whole process doesn’t last long (a few micro or milliseconds), but long enough to be registered by the microcontroller. When only a push-button is used as a counter signal source, errors occur in almost 100% of cases!

To prevent contact bounce I added some extra code. so we can get error less counting from this circuit. When you pressed and hold the Count button this circuit wont count.

PIC16F628A Datasheet

/******************************************************************************* 4 SSD Up Counter Copyright (C) 2015 Praneeth Kanishka This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses >> Email: scorpionzblog@gmail.com >> Web : http://scopionz.blogspot.com *******************************************************************************/ #define CLR PORTA.F4 #define ssd1 PORTA.F0 #define ssd2 PORTA.F1 #define ssd3 PORTA.F2 #define ssd4 PORTA.F3 void ssdecode(char i); int number=0; char digit1, digit2, digit3, digit4; char Loop=0; char key=0, last_key=0; void Delay_dis(){Delay_ms(5);} void main() { PCON.OSCF = 1; //4MHz CMCON |= 0x07; // Disable Comparators //INTCON = 0b10010000; TRISA = 0x10; TRISB = 0x01; PORTA = 0; PORTB = 0; Delay_ms(10); while(1){ if(!PORTB.F0) key=1; else {key=0; last_key=0;} if(key!=last_key) { if(++number>9999) number=0; last_key = key; } while(Loop <5) { ssdecode(digit1); //Display digit 1 ssd1 = 1; Delay_dis(); ssd1 = 0; ssdecode(digit2); //Display digit 2 if(number>9)ssd2 = 1; else ssd2 = 0; Delay_dis(); ssd2 = 0; ssdecode(digit3); //Display digit 3 if(number>99)ssd3 = 1; else ssd3 = 0; Delay_dis(); ssd3 = 0; ssdecode(digit4); //Display digit 3 if(number>999)ssd4 = 1; else ssd4 = 0; Delay_dis(); ssd4 = 0; Loop++; } Loop = 0; if(!CLR) number=0; digit1 = (number) %10; digit2 = (number/10) %10; digit3 = (number/100) %10; digit4 = (number/1000)%10; } } void ssdecode(char i) { switch (i) { case 0: PORTB = 0b01111110; break; case 1: PORTB = 0b00001100; break; case 2: PORTB = 0b10110110; break; case 3: PORTB = 0b10011110; break; case 4: PORTB = 0b11001100; break; case 5: PORTB = 0b11011010; break; case 6: PORTB = 0b11111010; break; case 7: PORTB = 0b00001110; break; case 8: PORTB = 0b11111110; break; case 9: PORTB = 0b11011110; break; } }