Timer Countdown Circuit with PIC

complet circuit count down timer
Countdown Timer


Circuit, Wiring | Project pictures


Flow chart | Source code

Project Specifications

  • PIC:PIC16F84A
  • Processor Frequency:10MHz
  • Range:1 to 99 minutes
  • Timer Set:BCD switches
  • Display:Minute:00-99 Seconds:00-59

Timer countdown every second controled bt hardware.
Time adjust with 2 BCD switches.
In countdown, control voltage value contact.
Led lights up in final countdown and relay turn ON/OFF external circuit.

Timer Display timer display

Circuit Diagram, PCB

Electronic circuit diagram - Timer countdown

Timer circuit Diagram
X1=10Mhz resonator.

Pattern drawing (component side)

PCB timer

Pattern drawing (wiring side)

PCB wiring timer
Green lines show wiring connections at component side.

Source code files - LED flasher

Timer source Code (ZIP) Timer HEX (ZIP)

Flowchart - Led Flasher

Flow chart showing software processing outline.
Processing can be understood read only source code list.
flasher flowchart

LED Flasher Board Pictures


component side PCB


wiring side PCB
Original Author: Seiichi Inoue (Japan)