本实验设计一个能够显示时、分、秒的数字时钟，时间在七段数码管上显示，显示数字为十进制数。通过开发板上的按键调整数字时钟的时间，分别用四个按键来控制分、时的增减，对于分、时的调整只影响本位，不产生进位或借位。各按键及数码管的功能要求如表1 所示。需要特别说明，因为开发板数码管的显示位宽不够，因此，通过一个开关进行切换选择（如：开,显示时分；关,显示分秒）。-When this experiment to design a display hours, minutes, seconds, digital clock, time on the seven-segment LED display, display numbers as a decimal number. By developing digital clock panel buttons to adjust the time, respectively, with four buttons to control the points, changes when, for the points adjustment affects only the standard, not a carry or borrow. Each key and digital functional requirements as shown in Table 1. Of particular note, because the development board digital tube display bits wide enough, so, through a toggle switch to　(eg: open, display division　off, show minutes and seconds).