8051 microcontroller를 이용한 7-segment stop watch구현

1. Purpose

In this experiment, we are going to design our own digital system to improve our design ability using 8051 microcontroller. We have to understand the interrupt operation of 8051 microcontroller. Though this process we are getting familiar with COMPACT51 / KEIL uVIsionII development environment for 8051 microcontroller.

2. Problem statement

(A) 7-Segment

Implement the stopwatch. The timer starts when INT0 button is pushed, and the timer stops when INT0 button is pushed again. The timer becomes “0.00” (cleared) when TIMER0 button is pushed. Time is represented by the three 7 segment LED modules. During the first 10 seconds, the leftmost module represents ‘second, the middle one represents ‘1/10 second, and the rightmost one represents ‘1/100 second. At this time, there is a decimal point between leftmost one and right 2 logics, i.e., between 1 second and 1/10 second. After 10 seconds, 2 left modules represent the ‘second level and the rightmost one represents ‘1/10 second. In other words, the position of a decimal point shifts right and the number of 1/100 second disappears. Then, the timer can represent up to 99.9 second.

(B) LED

During stopwatch operates, 8 LED modules present the number of 7 segment LED as binary number. 4 LED modules present multiples of 10 second, and other 4 LED modules present multiples of 1 second. For example, if number of 7 segment is 37.2, 8 LED modules should be 0xxx xxx1. Implement 0 as turned-off LED and 1 as turned-on LED. Dont express multiples of 0.1 second and 0.01 second, and express only multiples of 1 second and 10 second. When reset button is pushed, 8 LED modules should be turned off.