Basic Level     Skills: Not specified    


Project tested and working perfectly

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.

If you want to contribute your projects to website please email me at: contact[at]rickeyworld[dot]info

Tags Digital Countdown Timer7-segment countdown timer

94.57 kB





boy donald
27 Oct 2014: 15:17 PM
I want to ask , why when I try to change the time ( minute ) can not be executed . thank you .
29 Oct 2014: 00:57 AM
Dear sir, thanks before. i have some project urgent for my school and my project need this digital countdown timer using 7 segmen display. but your project only show ten minutes countdown, i need your help, can you show me more to change the minute or set the time manually. thank you, sorry for disturbing you. sorry for my bad english.
02 Nov 2014: 07:15 AM
You will need to make changes in the source as this is a static timer. For changeable timer you will also need to add keys and provision for timer storage.
boy donald
03 Nov 2014: 02:31 AM
thank you for replying. but the problem, I'm not too smart to add the key and change the terms of its time. i hope you can help my project, sory for my bad english.
03 Nov 2014: 04:48 AM
We cannot provide you ready code or something but we can help you implement it. You need to be a little smart to understand what we say and then implement. Please create a forum topic to get more help on this project. we cannot keep posting in comments area.
boy donald
03 Nov 2014: 11:15 AM
Thank you for your attention , now I begin to understand what you are saying.
01 May 2015: 06:42 AM
Hey I am mechanical eng student and I would like to make a countdown clock for my go-kart team but we need more digits , like MM,WW, DD, HH , mm , ss , ms (month , week , day , hour , minute , sec , milli sec) .. can anybody help and tell me to how make such thing in big scale ?
08 May 2015: 16:07 PM
@shaygan, Please post your question in forum. Thanks!
15 Jul 2015: 13:40 PM
Hello Sir.... Do you have the report for the Digital countdown timer?
20 Jul 2015: 04:44 AM
@Ashna If its not available in the ZIP file then we don't have it either. Whatever is submitted by the Author is uploaded here.
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Wed Dec 11 2019, 07:59 AM
Sarah Gold
I was recently on your site and I can see you continue to pour time and energy into your digital presence. Your hard work shows and it’s really coming along!
Thu Nov 21 2019, 12:30 PM
how to interface 8051 microcontroller with NRF24L01+ module
Sat Oct 12 2019, 10:23 PM
Log in.. then post your code in the 8051 forum
Sat Oct 12 2019, 10:18 AM
Bhadra Sajikumar
i am doing a countdown timer with 8051 for my project, unfortunately our professor had to take a leave of absence before he could teach us most of it.. can someone explain the .asm code of it for me?
Mon Sep 23 2019, 07:37 AM
I am doing a project for my schools wireless security system with cameras,sensors and spot lights using 8051 micro controller, could you help me out with the design and its source code.
Wed Sep 18 2019, 08:48 PM
Caryn Kover
Thank you for your time,
Mon Aug 05 2019, 07:09 PM
@Ismail in forum, give details
Mon Aug 05 2019, 04:33 PM
Ismail balghmi
Hello. Please I won't download
Wed Jul 24 2019, 12:47 AM
@BUSTER123 Please post in the forum
Tue Jul 23 2019, 06:13 PM
hello! newbie here. i am kind of a guy who hates using ready - made existing libraries, so this helped a lot as i was trying to control and write to a character lcd display. however, i can't figure out how to set the cursor position. for example, i want to set it to the 5th column in the first row, so position 5. so according to the table, i am sending 10000101 on the 8 data lines of the lcd (register select pulled low). the cursor does not move there however. and i cant move the cursor left or right too. is it something wrong that i am doing? thank you.



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