PIC16F628A based Electronic Combination Lock circuit schematic

PIC16F628A based Electronic Combination Lock circuit schematic

This electronic combination lock can be use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. The relay can operate a power to open type electric strike with a shorting contact or a power-to-hold type electromagnetic lock with a breaking contact (we need the relay because these locks usually work with AC, not DC). The code can be changed any time after entering the current code.

Current consumption of the circuit is low, because the PIC sleeps most of the time, and wakes up only for processing key presses. The 16F628A already contains an internal RC oscillator, so no crystal is needed.

• Type in the correct code and use # as 'enter'. The initial code is 623342. You can change the length of code as well.
• * is used to change the code. Type in the actual code then press *. If you didn't miss the actual code, the code change indicator LED will light up. Then type in the new code twice.

I am using 3x3 keypad you can also use 3x4 keypad(connect col4 with pin13) to complicate your password.

Downloads: Code files

Schematic:

Combination Lock using PIC16F628A

Components Required:

U1, PIC16F628A

U2, 74HCT164

R1, 330 ohm

R2, 1k ohm

D1, Red LED

D2, 1N4148

RL1, 9/12v relay

Q1, BC547

LCD, 16x2 LCD

keypad, 3x3 / 3x4

BUZ1, 5v buzzer