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Want to know how NI implemented the FPGA-based digital phosphor in its new VirtualBench All-in-One Instrument? Here’s how

Xilinx Employee
Xilinx Employee
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National Instruments (NI) is already on its 2nd-generation of its successful, Zynq-based VirtualBench All-in-One Instrument and one of the new features is digital phosphor for the built-in, 4-channel digital oscilloscope. Now this is an increasingly common feature of high-end digital scopes and NI added a Xilinx Kintex-7 FPGA to the original VirtualBench design to add features including digital phosphor, which helps you to see rare events occurring by overlaying and displaying large numbers of signal captures on one screen. The NI implementation uses intensity grading so that you can see how often data points recur within the overlaid signal captures.


I captured Senior Hardware Engineer Dane Wagner at NI Week, held in Austin this week, and he explained how he implemented this new feature in the 2nd-generation VirtualBench VB-8034. The VirtualBench VB-8034 accumulates all of the captures in a new, dedicated DDR3 SDRAM attached to the Kintex-7 FPGA. The FPGA performs all of the digital phosphor rendering in real time while the VB-8034 is capturing and displaying the data. Among the many things the Kintex-7 FPGA is doing are 16x interpolation to connect the dots (captured data points) and FIR filtering. According to Dane, that all requires “a lot of multiplies.”


He also explains that part of the digital phosphor algorithm requires performing 256-bit adds, which are split into two 128-bit adds and pipelined in his FPGA implementation. This made “timing a snap” he says. The availability of Xilinx IP like the MIG Memory Interface Generator allowed him to focus his attention on developing cool algorithms to make the data look good.


Here’s a 6-minute video with Dane’s demo and explanation:







For more information on the NI’s VirtualBench All-in-One Instrument and the VB-8034, see:










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