The Software-Designed Vector Signal Transceiver
NI introduced the world’s first software-designed instrument, the NI PXIe-5644R vector signal transceiver (VST), at NIWeek 2012. A second VST, the NI PXIe-5645R, which includes a baseband I/O interface, was released shortly thereafter. In addition to the small size and high performance of the RF hardware, the VST was revolutionary in that end users could program the device’s FPGA through NI LabVIEW system design software (see Figure 1). This approach greatly increases flexibility beyond vendor-defined instruments and better meets application demands with additional FPGA-based processing and control.
Figure 1. Compare the software-designd approach of the VST with traditional approaches.
NI later added VST hardware support to its full-featured NI-RFSA and NI-RFSG instrument drivers for maximum compatibility with existing applications as well as cellular and wireless measurement software. This instrument driver support required a fixed, precompiled FPGA personality, which introduced a trade-off between maximum compatibility through NI-RFSA and NI-RFSG programming and maximum flexibility when designing a completely custom instrument in the LabVIEW FPGA Module.
Introduction to Instrument Driver FPGA Extensions
NI is now introducing instrument driver FPGA extensions, a new feature of the NI-RFSA and NI-RFSG instrument drivers you can use to customize the VST FPGA capabilities in LabVIEW while preserving the full feature set of the instrument driver APIs (see Figure 2).
Figure 2. Instrument driver FPGA extensions bridge between the unparalleled flexibility of an open FPGA and the compatibility of standard instrument drivers. You get the best of both worlds in a user-friendly way.
An abstraction layer in the FPGA source code implements the default FPGA capabilities required by the NI-RFSA/RFSG API while exposing the relevant control and data signals necessary to enhance automated test applications. Test engineers can add application-specific FPGA IP to the base VST FPGA design and then independently control this IP from their host programs in parallel with NI-RFSA/RFSG API calls, as demonstrated in Figure 3 below.
Figure 3. Application-specific FPGA IP added to the base VST FPGA design can be independently controlled from host programs in parallel with NI-RFSA/RFSG API calls.
This architecture enables a variety of application-specific enhancements that take advantage of the parallelism, low-latency control, and processing performance of the VST FPGA. These enhancements include custom and/or novel instrument capabilities such as frequency mask triggering; better system integration through hardware-timed device under test (DUT) control and the deterministic triggering of other instruments; accelerated test throughput with FPGA-based measurements and coprocessing; and even closed-loop or protocol-aware tests in which the instrumentation hardware responds to the DUT in real time.
Simple Custom Trigger Use Case
For example, a user may want to implement a custom trigger that waits for a digital signal from the DUT before acquiring data. Figure 4 below shows how instrument driver FPGA extensions and LabVIEW FPGA significantly abstract the complexity of making such a modification to the FPGA.
Figure 4. Example modification to the NI-RFSA input loop in LabVIEW FPGA to implement custom triggering from a DUT.
In Figure 4, a digital signal from the DUT is easily accessed through a LabVIEW FPGA I/O node, and is combined with the default reference trigger made available through the FPGA-based NI-RFSA Trigger VI. The simplicity of this modification demonstrates how when using instrument driver FPGA extensions, you don’t have to understand the complete firmware and driver architecture to make such changes to the FPGA.
Precompiled FPGA Personalities from National instruments
Today, you can download precompiled FPGA personalities that use instrument driver FPGA extensions from ni.com/vst/getting-started/. These include the necessary host examples and application IP that demonstrate how to take advantage of the FPGA enhancements for common applications.
You can also register to participate in the Instrument Driver FPGA Extensions Early Access Program at ni.com/beta so you can build your own custom VST personalities, which are compatible with NI-RFSA and NI-RFSG. Pick and choose from application IP on ni.com or build your own to create a customized, software-designed instrument tailored to your automated test application.
- Download and run pre-compiled instrument driver FPGA extensions for your VST at ni.com/vst/getting-started/.
- Read more details on how to use instrument driver FPGA extensions.
- Hittite Microwave has reduced their RF IC test cost and increased test speed using instrument driver FPGA extensions. Read the case study.
- Sign up for the Early Access Program at ni.com/beta.