sir,
can you help me how to write a program for timer with dot matrix LED using 8051 microcontroller in assembly langauage

countdown timer for lcd using 8051 microcontroller

A countdown timer is a down counter that counts from a specified time to 00:00. It is used in many devices such as washing machine, televisions, microwave ovens, etc. This countdown timer has three states: the running state where it counts down, the pause state where it displays the paused time and the reset state to set the countdown. The countdown is displayed on a set of four seven segment displays using the 8051 microcontroller (AT89C51). A buzzer sounds when the countdown gets over.

A very simple Digital countdown timer using 8051 and 7 segment displays. A perfect project for microcontroller starters.

Author has used BCD to 7-segment decoder for driving displays. each segment has its own decoder. so there is no multiplexing included for displays. Additionally there are 2 control switches one to Start/Pause and second to Reset the timer. There is a Buzzer added to indicate timer has expired.

The code for this project is written in assembly language. Timer 0 is used for 1 second timer delay. Code is written for a hardcode 10 minutes timer. So there is a lot of scope to expand this project according to your needs. You can take this project as a reference if you want to develop more on it.

The zip file includes code, schematic and proteus simulation file incase you want to try project before building it. Complete list of files in given below:

File List information:
1. Timer.asm - Assembly code for project.
2. timer.hex - Pre-assembled hex file.
3. Digital Countdown Timer.png - Schematic/circuit diagram
4. Digital Countdown Timer.DSN - Proteus simulation file
5. timersimulation.png - Simulation screenshot

Incase you have any doubts regarding this project please make use of forum: Rickey's World forum

Thanks to Prasad.K.Wagh (Kartikceleb) and his team for this contribution.