SPI接口的vhdl代码，可以实现与单片机的spi通信，完整的工程

dataflow muliplexer in FPGA

说明：  基于FPGA的用verilog语言写的，改程序可产生不同调制系数和不同频率的AM波，长按按键切换调制度25 、50 、75 和短按按键切换调制信号频率1k、1.5k、2k、2.5k.(Based on the FPGA using verilog language, change the program can produce different coefficients and different frequency modulated AM wave, long press the button to switch the modulation of 25 , 50 , 75 and short press button to switch the modulation signal frequency 1k, 1.5k, 2k, 2.5k.)

一个简易的频率计，主要用检测在一定范围内的频率，当然频率过大会有误差(A simple frequency meter, mainly used for testing in a range of frequencies, of course, frequency of errors over the General Assembly)

EDA 正弦信号发生器：正弦信号发生器的结构有四部分组成，如图1所示。20MHZ经锁相环PLL20输出一路倍频的32MHZ片内时钟,16位计数器或分频器CNT6，6位计数器或地址发生器CN6，正弦波数据存储器data_rom。另外还需D/A0832（图中未画出）将数字信号转化为模拟信号。此设计中利用锁相环PLL20输入频率为20MHZ的时钟，输出一路分频的频率为32MHZ的片内时钟，与直接来自外部的时钟相比，这种片内时钟可以减少时钟延时和时钟变形，以减少片外干扰 还可以改善时钟的建立时间和保持时间，是系统稳定工作的保证。CNT6用来将32MHZ进行8分频得到4096HZ的频率提供给CN6与data_rom时钟信号。由CLK端输入20MHZ的时钟信号，在DOUT端就可输出稳定的正弦信号。(Sine signal generator has the structure of four parts, as shown in figure 1 below. The 20 MHZ phase lock loop PLL20 output all the way of frequency doubled within 32 MHZ slice clock, 16 counter or prescaler CNT6, six counter or address generator CN6, sine data storage data_rom. In addition to D/A0832 (shown in not draw) will digital signal into analog signals. This design using the phase lock loop PLL20 input frequency for 20 MHZ clock, the output of the frequency of all points frequency of 32 pieces (MHZ clock, and comes directly from the external clock, compared to this piece of clock can reduce the clock in delay and clock deformation, to reduce the interference of Can also improve the establishment of the clock time and keep time, is the system stability of assurance. CNT6 used to will and to 8 MHZ get 4096 HZ dividing the frequency to provide CN6 and data_rom clock signal. The input by CLK 20 MHZ clock signal, in DOUT end can output stable sine signals. )

一个很好的利用verilog编程实现的cpu程序，一定要好好利用。-a good use of the Verilog Programming cpu procedures, we must make good use of.

实现了UART的底层协议，加入了控制器，其波特率可以根据使用进行调整；发送模块、接收模块相互独立，互不影响。(Realization of the underlying protocol UART, joined the controller baud rate can be adjusted according to use transmission module, receiver module are independent of each other.)

VHDL基本运算，采用8位为乘法器，将两个8位字符串的值输入相乘后

本书通过100个实例，详细介绍便件描述语言vHDL的各种语法现象及其在专用集成电路(AHc)设计蝴还中的使用方法。(the book through one hundred examples, it detailed description language vHDL pieces of the phenomenon and its various grammatical in ASIC (AHc) were also designed butterfly The usage.)

利用康芯公司的FPGA芯片设计制作频率计，实现对频率的测量。(Kang core using FPGA chip design company frequency meter, realize the frequency measurements.)

该例程是PC机通过FX2-CY7C68013-A的USB2.0控制芯片与FPGA实现通信。其中的工程和代码包括PC机上的USB固件程序、驱动程序、上位机程序，FPGA上的VERILOG通信程序。(The routine is a PC, through the FX2-CY7C68013-A of the USB2.0 controller chip and the FPGA to achieve communication. One of the projects and code, including PC, the USB firmware, drivers, FPGA' s Communication Program)