实验平台说明：安装了NI LabVIEW 2015 32bit版本，安装了NI FPGA Interface C API Generator，安装了硬件PCIe-7842R；安装了Visual Studio 2015(下载的C API Generator说明是针对VS2013，不过实验测试发现vs2015可以使用)；按照官网给的例子进行实验http://www.ni.com/tutorial/8638/en/，只测试了FPGA板卡模拟输入功能，没有写模拟输出功能。官网例子是采用NI公司的LabWindows/CVI上位机软件。
实验步骤：
- 在LabVIEW中新建FPGA工程，命名为FPGA.vi
此工程中，FPGA和上位机有四个接口：3个参数输入接口（Samples等等），1个数据读取接口（FIFO），接口通信通过PCIe进行。编译该工程，得到bitfile文件
2.打开FPGA Interface C API Generator，导入之前用LabVIEW编译生成的FPGA bitfile，点击generate，生成了几个个文件：1.FPGA bitfile; 2.NiFpga.c;3.NiFpga.h;4.NiFpga_FPGA.h；
其中NiFpga_FPGA.h包含了应用程序中函数调用需要的常量，和上述读写结构的地址信息
NiFpga.c和NiFpga.h对所有工程都是一样的，包含了调用NI FPGA的各种系统函数。
3.新建visual studio控制台应用程序，添加上述几个文件
4.NiFpga.c设置编译属性，选择No Precompile,如下。（如果不这样设置，编译的时候会因C/C++编译问题而报错）
5.编译上位机程序，主要是打开FPGA(完成下载bitfile到FPGA的任务)，按照地址读写FPGA中的接口，关闭FPGA等操作。测试程序如下：
// ConsoleApplication1.cpp : Defines the entry point for the console application.
//
// NIFPGATest.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "NiFpga_FPGA.h"
#include <malloc.h> int main()
{
/* must be called before any other calls */
printf("Initializing...\n");
NiFpga_Status status = NiFpga_Initialize();
if (NiFpga_IsNotError(status))
{
NiFpga_Session session;
/* opens a session, downloads the bitstream, and runs the FPGA */
printf("Opening a session...\n");
/* opens a session, downloads the bitstream, but does not run the FPGA */
NiFpga_MergeStatus(&status, NiFpga_Open(NiFpga_FPGA_Bitfile, NiFpga_FPGA_Signature,
"RIO0", NiFpga_OpenAttribute_NoRun, &session));
if (NiFpga_IsNotError(status))
{
/* declare variables for output and input */
double numSamples, aorate, airate;
uint16_t threshold = ;
uint32_t r, timeout = /* 10 seconds */;
NiFpga_Bool overLimit;
int16_t *data = NULL;
numSamples = ;
airate = ;
/* allocate size for the samples to read */
data = (int16_t*)malloc(sizeof(int16_t) * numSamples); /* write the number of samples and loop rate to the FPGA VI */
NiFpga_MergeStatus(&status, NiFpga_WriteI32(session, NiFpga_FPGA_ControlI32_Samples, numSamples));
NiFpga_MergeStatus(&status, NiFpga_WriteU32(session, NiFpga_FPGA_ControlU32_LoopPeriod, airate));
NiFpga_MergeStatus(&status, NiFpga_WriteI16(session, NiFpga_FPGA_ControlI16_Threshold, threshold)); /* run the FPGA application */
printf("Running the FPGA...\n");
NiFpga_MergeStatus(&status, NiFpga_Run(session, )); /* read the DMA FIFO */
NiFpga_MergeStatus(&status, NiFpga_ReadFifoI16(session, NiFpga_FPGA_TargetToHostFifoI16_FIFO,
data, numSamples, timeout, &r)); /* read the Over Limit? boolean */
NiFpga_MergeStatus(&status, NiFpga_ReadBool(session, NiFpga_FPGA_IndicatorBool_OverLimit,
&overLimit)); /* close the session now that we're done */
printf("Closing the session...\n");
NiFpga_MergeStatus(&status, NiFpga_Close(session, ));
}
/* must be called after all other calls */
printf("Finalizing...\n");
NiFpga_MergeStatus(&status, NiFpga_Finalize());
}
/* check if anything went wrong */
if (NiFpga_IsError(status))
{
printf("Error %d!\n", status);
printf("Press <Enter> to quit...\n");
getchar();
} return status;
}
参考文献：
- 官网给出的R系列FPGA的C API用法说明http://www.ni.com/tutorial/8638/en/
- 电脑上给出的FPGA Interface C API Generator的example
