设计功能：

1．.用VHDL完成12位十进制数字频率计的设计及仿真。

2．频率测量范围：1Hz∼ 10KHz，分成两个频段，即1∼ 999Hz，1KHz∼ 10KHz，用三位数码管显示测量频率，用LED显示表示单位，如亮绿灯表示Hz，亮红灯表示KHz。

3．具有自动校验和测量两种功能，即能用标准时钟校验、测量精度。

4．具有超量程报警功能，在超出目前量程档的测量范围时，发出灯光和音响信号。

-Design features: 1. . Complete with VHDL 12-bit decimal digital frequency meter design and simulation. 2. Frequency Range: 1Hz ~ 10KHz, divided into two bands, namely, 1 ~ 999Hz, 1KHz ~ 10KHz, with three digital display measuring frequency, with LED display that unit, such as the green light that Hz, red light, said KHz. 3. Calibration and measurement with automatic two functions, namely, the clock can use the standard calibration, measurement accuracy. 4. Super-range alarm function, beyond the scope of the present range of measurement files, the issue of light and sound signals.