Door entry audio alarm with door number display on a 7 segment display.

Experiment Name: Door entry audio alarm with door number display on a 7 segment display.

Objective of project: To learn how to program a microcontroller using assembly language for door entry audio alarm and door number in a seven segment display.

Circuit Diagram:

Components:

● AT89C51 Microcontroller

● Bread  board

● 9V DC battery

● Common Anode 7 segment Display

● Resistors -8.2k

● Transistor BC547(NPN)

● 33pF Ceramic capacitors x 2 

● 11.0592 MHz crystal

● 10μF Electrolytic capacitor

● Push switch

● UM66 musical IC

● Buzzer

● Jumpers

● Connecting wires

● Voltage regulator

Flowchart of program:

Code:

Brief description of program: 

I. Firstly, load 0-7 digit codes of 7 segment display into data pointer

II. Configure p3 port as input and p1 as 7Fh

III. Move the value of P3 into accumulator and compare whether it is equal to 0FFh

a. If not equal then go to open

b. Else repeat III.

IV. Complement accumulator and initialize a counter R0

V. Repetitively right shift carry the accumulator and increment counter until carry is 1.

VI. When carry is 1, retrieve door code from data pointer and show it to segment display. And give signal to the buzzer.

See the project at https://youtu.be/8sqcv9dR-Fo