/**
Project name : Clock;
Data : 2020 April 2;
Function : A clock for millisecond precision,
4 keys modify Clock parameter;
KEY0 is pause key under running mode and add one under settings mode
KEY1 is right key under settings mode
KEY2 is lift key under settings mode
KEY3 is set key
Hardware : DE2-115;
Development environment : Quartus II 15.0;
FPGA type: EP4CE115F29C7;
System frequency : 50MHz;
Company :
Author :
Hardware simulation :
Modification record :
*/
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