Faster Digital Communication and Advanced Digital Test Techniques with NI PXIe-6547/48 Modules

Publish Date: Dec 03, 2009 | 3 Ratings | 4.00 out of 5 |  PDF

Overview

The NI PXIe-6547 and PXIe-6548 digital waveform generator/analyzers feature 32 single-ended channels with clocking rates up to 200 MHz. You can perform double data rate (sampling on both the rising and the falling edges) on these modules to achieve data rates of up to 400 Mbits/s for generation and 300 Mbits/s for acquisition. These modules have selectable voltage levels ranging from 1.2 to 3.3 V in 100 mV steps. You can also use the onboard high-resolution direct digital synthesis (DDS) clock to achieve arbitrary clock rates for your unique applications.

Table of Contents

  1. Advanced Features on the NI PXIe-6547 and PXIe-6548
  2. Applications
  3. Summary
  4. Related Links

Figure 1. The NI PXIe-6547 and PXIe-6548 are PXI Express-based instruments featuring clock rates up to 100 and 200 MHz, respectively.

 

1. Advanced Features on the NI PXIe-6547 and PXIe-6548

1. Direction control: The NI PXIe-6547/48 modules feature per-channel, per-cycle direction control. This means you  can not only configure each channel  for input or output independently but also change direction dynamically on a per-cycle basis. For example, on a 200 MHz clock, you can change state every 5 ns.

2. Onboard hardware compare: These modules feature onboard, real-time hardware compare, which is ideal for a stimulus-response application. You can send a stimulus waveform to a device under test (DUT) and compare response data, either on the same channel or on other input channels. This feature combined with per-cycle direction control allows for bit error rate testing; custom protocol communication such as SPI, I2C, and JTAG; or stimulus-response tests.

You can perform hardware compares at up to 200 MHz on 24 channels. The stimulus/generation data is stored on an onboard first-in-first-out (FIFO) memory buffer. The response data is then compared with the stored stimulus data on the hardware itself. You can access the error locations and samples in the NI-HSDIO API. The device also generates an error event, which you can use with the advanced scripting engine for real-time decision making.

 

Figure 2. You can perform onboard hardware compares using the NI PXIe-6547 and PXIe-6548.

 

>> Download an example on using the hardware compare with scripting engine here: Hardware Compare with Scripting on a National Instruments High Speed Digital I/O Board

3. Multiple banks of data delay: Many digital interfaces or PCBs have multiple traces with different lengths running on them. At hundreds of megahertz, small differences in trace lengths can cause skew between channels, where parallel data might not arrive at the DUT at the same time because of the skew caused by the different trace lengths. You can account for this by using the data delay feature of the NI 654x/5x/6x devices. The NI PXIe-6547/48 modules feature three distinct banks of data delay that you can use to phase shift your data channels with picoseconds of resolution at these three distinct values.

You can use this feature to calibrate traces on a load board, perform rise time and fall time measurements, or even account for setup and hold times.

Figure 3. The NI PXIe-6547/48 modules feature multiple banks of data delay for advanced timing tests and calibration requirements.

In addition, you can use the synchronization capabilities of digital devices with data delay capabilities to achieve even more distinct data delay values. As an example, you can synchronize two digital modules to get more than three banks of delay. Moreover, you can programmatically select the synchronization offset between the two modules using the NI-TCLK API. This is shown in Figure 4.



Figure 4. You can synchronize multiple modules to achieve more banks of data delay.

4. Double data rate: You can clock data at both the rising and falling edges of the sample clock to achieve double data rate (DDR). You can achieve up to 400 Mbits/s for generation (DDR on a 200 MHz clock) and 300 Mbits/s for acquisition (DDR on a 150 MHz clock). To view a complete table on the different data rates you can generate, see the NI PXIe-6547/48 specifications document.

5. Scripting: You can load multiple predefined waveforms onto the onboard memory of NI PXIe-6547/48 modules. With scripting, you can loop and link through these preloaded waveforms in real time, without any software lag. Here is an example of such a script.

script upOnesOrDown

    generate countUp

    if scripttrigger0 then

        generate allOnes

    else

        generate countDown

    end else

end script

As you can see, you can not only control different waveforms but also make onboard decisions based on triggers and events.

See Also: Advanced Features of High-Speed Digital I/O Devices: Scripting in High-Speed Digital I/O Instruments

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2. Applications

Faster data rates, flexible voltage levels, onboard hardware compare, and advanced timing and synchronization features make the NI PXIe-6547/48 modules ideal for a large variety of applications.

Semiconductor/electronic test: NI modular instruments provide a unique advantage because you can synchronize them with other analog and digital instruments to create a highly synchronized mixed-signal test system. With the high clock rates on the NI PXIe-6547 and PXIe-6548, you can interface with faster semiconductor chips and components.

 

Figure 5. You can use the NI PXIe-6548 with an NI 2515 high-speed digital signal insertion switch to perform dynamic, linear, or parametric tests on a digital-to analog converter (DAC).

 

Figure 6. This NI LabVIEW front panel shows the dynamic characteristics of a DAC. Use the NI PXIe-6548 to generate digital data to the DAC.

 

Multimedia/electronics testing: These devices are also ideal for multimedia testing such as high-definition (HD) video testing, which requires high data throughput. With streaming rates of up to 660 MB/s for acquisition, you can test HD signals such as 1080p at up to 60 Hz refresh rates. Using the per-pin, per-cycle direction control, you can communicate with protocols such as SPI and I2C or custom digital protocols. You can change the state on the line dynamically on a per-cycle basis. These devices are mostly used as master devices on these buses, but you also can use them as slaves in certain scenarios.

Logic Analyzer/Pattern Generator: These digital devices feature superior software support and APIs, making them easy to use for general-purpose pattern generator/logic analyzer applications. You can use the NI-HSDIO driver with programming languages such as NI LabVIEW, NI LabWindows™/CVI, or ANSI C to create custom user interfaces.

Logic Analyzer/Pattern Generator Bundle

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3. Summary

The NI PXIe-6547 and PXIe-6548 make it possible to expand your digital applications, whether you need higher speed, higher data throughput, or more advanced capabilities. At 200 MHz on 32 channels, with advanced features such as hardware compare, multiple banks of data delay, and an onboard DDS clock, these devices are ideal for a large variety of digital applications. You can also synchronize multiple devices to increase channel count or synchronize multiple analog and digital devices to create a highly synchronized mixed-signal system.

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4. Related Links

Advanced Features of High-Speed Digital I/O Devices: Data Delay

Top 10 Considerations for Your High-Speed Digital Application

 

The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft Corporation in the United States and other countries.

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