Microcomputer System Project 3

This repository contains an 8051 assembly stopwatch project built for a microcomputer systems course. The project uses an external interrupt for user input, Timer 0 for timekeeping, and a 1602 LCD module for output.

Project Overview

The stopwatch is implemented in assembly language for the 8051 microcontroller family. It initializes the LCD, displays the current stopwatch value, and updates the time in fixed intervals. A user button connected to INT0 toggles the stopwatch between paused and running states.

From the available source code, the stopwatch logic is based on:

• Timer 0 in mode 1
• INT0 external interrupt input
• PSW.5 as the running or paused state flag
• PSW.1 as an interrupt control flag
• A 1602 LCD connected through ports P1 and P2

Hardware Mapping

The LCD control and data lines are defined in the assembly source as:

• P1.0 -> LCD_RS
• P1.1 -> LCD_RW
• P1.2 -> LCD_E
• P2 -> LCD_DATA

Stopwatch Behavior

The program initializes the LCD and starts from 00:00:00. The display is updated digit by digit as the timer advances. The source code indicates that:

• the stopwatch can be paused and resumed with the external interrupt
• timing is accumulated using Timer 0 reload values
• the displayed value is formatted like a digital stopwatch
• the implemented counting range is approximately up to 3 minutes

Repository Structure

stable/
  project3_stable.asm
  project3_stable.adf
  project3_stable.bin
  project3_stable.hex
  project3_stable.lst

unstable/
  project3_unstable.asm
  project3_unstable.adf
  project3_unstable.bin
  project3_unstable.hex
  project3_unstable.lst

submission/
  project3_final.asm
  demo_video.mp4
  microcomputer-system-project-3.pptx

File Groups

stable

This folder contains the stable version of the project and its generated output files.

unstable

This folder contains an unstable or experimental version of the project and its generated output files.

submission

This folder contains the final submission materials, including:

• the final assembly source
• the project demo video
• the project presentation slides

Notes

• The repository keeps both source files and generated build artifacts because they are part of the original course project deliverables.
• Some original source comments appear to have character encoding issues, but the program structure and purpose remain identifiable from the code.