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。

-1 completed 12 with VHDL design and simulation of decimal digits of frequency. 2 Frequency Measurement Range:. 1Hz ~ 10KHz, divided into two bands, namely 1 ~ 999Hz, 1KHz ~ 10KHz, with three digital display measuring frequency, with LED display indicates the unit, such as a green light indicates Hz, red indicates KHz . 3 with automatic calibration and measurement two functions, namely, use standard clock calibration, measurement accuracy. 4 with over-range alarm function, when beyond the current range for the measurement range, emit light and sound signals.