用VHDL语言实现的计时器，最大计时为24小时，计时精度为1ms，设有复位和暂停功能，使用的晶振频率为50Hz。-VHDL language implementation of the timer with a maximum time of 24 hours, timing accuracy of 1ms, with reset, and pause functions, using the crystal oscillator frequency is 50Hz.