设计一个可以顺计时和倒计时的秒表。要求计时的范围为00.0S~99.9S，用三位数码管显示，用三个发光二极管正确显示以下状态：倒计时状态、顺计时状态、待机状态-Designed to be a cis-timing and countdown stopwatch. Required time ranges from 00.0S ~ 99.9S, with three digital tube display, with three light-emitting diode display cor

设计一个可以顺计时和倒计时的秒表。要求计时的范围为00.0S~99.9S，用三位数码管显示。用VHDL语言-Designed to be a cis-timing and countdown stopwatch. Required time ranges from 00.0S ~ 99.9S, with three digital tube display.

Proteus仿真，模拟了秒表倒计时功能-Proteus simulation, simulated countdown stopwatch function

本秒表计时器用于体育竞赛及各种要求有较精确时的各领域。此计时器是用一块专用的芯片，用VHDL语言描述的。它除开关、时钟和显示功能以外，它还包括1/100s计时器所有的控制和定时功能，其体积小，携带方便。(The stopwatch timer is used in sports competitions and in various fields where requirements are more accurate. This timer is written in a VHDL langu