NI矢量信号收发器的FPGA编程

VST Streaming项目样例提供两个主机样例。较简单的一个样例把从VST处采集得到的增多的或者连续的波形数据传输至VST进行生成，。比较高级的样例说明了多个VST的MIMO同步。

图 16.这些样例说明了VST Streaming项目样例的主机接口

4. 仪器驱动FPGA扩展

仪器驱动FPGA扩展提供了一种兼容NI-RFSA和NI-RFSG仪器驱动的VST FPGA编程方法。FPGA上的抽取层实现了所需要的仪器驱动功能，同时提供接口以改善具体应用的FPGA。虽然不像仪器设计库的直接编程那样灵活，然而 仪器驱动FPGA扩展支持的修改类型与标准信号分析仪和信号发生器的基于记录的采集和生成模式相一致。

图 17. 仪器驱动FPGA扩展架构包含VST仪器设计库，并且增加了一个抽取层以保护组件。用户IP不在此代码中，由主机进行控制，并且不受预编译封闭源NI-RFSA和NI-RFSG的影响

5. 大型FPGA开发考虑事项

The Virtex-6 LX195T FPGA on the NI PXIe-5644R and the NI PXIe-5645R is a large FPGA, though the full suite of instrument design libraries consumes a considerable fraction of the available resources. As such, compilation times can take 5 hours or more when using the NI LabVIEW FPGA Compile Cloud Service, depending on the complexity and resource utilization of the FPGA design. Furthermore, FPGA compilation is a non-deterministic process, and as a design consumes more FPGA resources, the repeatable compilation success rate drops below 100%. For such designs, initiating multiple compiles in parallel can help to ensure a successful compilation in approximately the same time as a single compilation. Table 3. provides some estimates for the different FPGA designs discussed in this paper.

表3. 各种VST FPGA设计的编译时间、成功率和FPGA占用率。