基于EDA技术设计4位十进制数字频率计的系统方案

protel经典教程，并附有一张电路设计原理图(protel classic tutorials, together with a circuit design schematic)

说明：  直接数字式频率合成器DDS设计、Verilog。 产生的信号可以是正弦波或方波、三角波、锯齿波等，自选。 采用DDS技术，将所需生成的波形写入ROM中，按照相位累加原理合成任意波形。 此方案得到的波形稳定，精度高，产生波形频率范围大，容易产生高频。 本实验在设计的模块中，包含以下功能： （1）通过 freq 信号输入需要的频率的值； （2）通过 wave_sel 信号选择所需的波形； （3）通过 amp_adj 信号选择波形放大的倍数。(DDS design of direct digital frequency synthesizer, Verilog. The generated signal can be sinusoidal or square wave, triangular wave, sawtooth wave and so on, optional. By using DDS technology, the required waveforms are written into ROM, and arbitrary waveforms are synthesized according to the principle of phase accumulation. The waveform obtained by this scheme is stable, accurate and easy to generate high frequency waveform. This experiment includes the following functions in the designed module: (1) Input the required frequency value through freq signal; (2) Choosing the required waveform by wave_sel signal; (3) Select the multiplier of waveform amplification by amp_adj signal.)

用Verilog HDL语言进行HDB3编码，并通过Quartus Ⅱ仿真验证(With the Verilog HDL language HDB3 coding, and simulation by Quartus Ⅱ)

FPGA VERILOG 用DCFIFO实现 跨时钟域的数据传输，已验证，直接可用-FPGA VERILOG using DCFIFO realize cross-clock domain data transfer, has been verified, directly available

流水线乘法器与加法器 开发环境：Modelsim（verilog hdl）(Multiplier and adder pipeline development environment: Modelsim (verilog hdl))

说明：  介绍USB PHY接口中的UTMI接口， 对使用Verilog进行USB接口编程具有帮助。(This paper introduces UTMI interface in USB PHY interface. It is helpful for programming USB interface with Verilog.)

流水线乘法器的VHDL实现，希望对你会有用！-Pipelined multiplier in VHDL implementation, you will want to use!

超低速的光纤一体发接收发送器,同于以前的光纤一体化接头都只适用于2M以上的通讯,如需将232等低速信号用光纤传输出,需要加复杂的调制解调电路,网动光电新生产的这款光纤头主要针对低速信号,可以传送DC-500KPS的信号,极大地简化了硬件设计.(Ultra-low-fat whole-speed fiber-optic transmitter receiver with fiber-optic integration in the previous joint only applies to more than 2M communications, etc. For the 232 low-speed optical fiber transmission of signals, the need to increase the complexity of the modulation and demodulation circuit, the net move Photoelectric new production of this first major response to low-speed fiber-optic signal, DC-500KPS can send the signal, greatly simplifying the hardware design.)

FPGA上的一个半加器实例程序，通过测试，可以直接运行在fpga开发板上。(One and a half adder example on FPGA program, through the test, can be run directly on the FPGA development board)

这是“VHDL设计”讲稿，希望对初学者有用，-"VHDL design" script, useful for beginners, thank you! !