Creating Real-Time Stimulus/Response System for the Blackfin ADSP-BF537 Evaluation Board

The Blackfin® ADSP-BF537 EZ-KIT Lite® evaluation board is equipped with an I/O connector, based on National Instruments Educational Laboratory Virtual Instrumentation Suite that connects to National Instruments data acquisition hardware or National Instruments ELVIS workstations. This document explains the input/output signal options for the audio codecs on the Blackfin ADSP-BF537 EZ-KIT Lite evaluation board. This document also discusses different methods for creating real-time stimulus/response systems for this board.

Virtual Instrumentation for DSP Developers

National Instruments pioneered the revolutionary approach to test and measurement called virtual instrumentation. With virtual instrumentation, engineers use software to define the functionality of modular hardware, such as a data acquisition, to quickly create user-defined measurement devices. Through a flexible software environment, the user-defined measurement system delivers data acquisition, analysis, and data presentation that exactly match the needs of the device you are testing. The Blackfin ADSP-BF537 EZ-KIT Lite ELVIS I/O connector is built on the concept of virtual instrumentation, which allows you to extend the functionality of a PC and transform it into an analysis tool for DSP designs.

Driver software is the layer of software that directly programs the registers of the DAQ hardware and manages its operation and integration with computer resources, such as processor interrupts, DMA, and memory. The majority of DAQ applications use driver software to interface the development environment, such as LabVIEW, to the DAQ hardware. Driver software hides the low-level, complicated details of hardware programming to provide you with an easy-to-understand interface or a stand-alone application program. The Blackfin ADSP-BF537 EZ-KIT Lite includes examples that use LabVIEW and NI-DAQmx driver software to build stand-alone measurement executables. Because plug-in DAQ devices do not have displays attached directly to the hardware like traditional oscilloscopes or multimeters, the software is the user interface to the system. The software integrates the transducers, signal conditioning, DAQ hardware, and analysis hardware into a complete, functional DAQ system.

The key component to a virtual instrumentation system is an integrated software framework that delivers a modular structure for building high-performance, automated measurement and control systems. For maximum performance, ease of development, and system-level coordination, the components of the framework must be independent, yet tightly integrated. This modular, integrated structure empowers you to rapidly build and easily modify measurement systems as system requirements change. Developing a measurement and automation system with a tightly integrated software framework delivers numerous benefits, including:

• Significantly increased productivity throughout the development, deployment, maintenance, and modification process with rapid application development tools designed for measurement and control applications.
• Higher performance measurement and automation systems, because the tools at each level are designed to work together to deliver maximum system performance.
• More tightly integrated systems brings together numerous diverse measurement devices into high-level systems that connect easily to other processes throughout the organization.
• Decreased costs throughout the product life cycle.

The Measurement and Control Services Software shown in Figure 1 plays a critical role in delivering a modular computer and networked-based measurement system. The components of this software--flexible high-level application programming interfaces (APIs), integrated driver engines, and a configuration manager--must all integrate within an application development environment (ADE), such as LabVIEW, for maximum system performance and development productivity. The specific tasks of the Measurement and Control Services Software include integration of measurement devices, as well as local and distributed configuration and programming of the measurement devices. For more information regarding the Measurement and Control Services Software framework, read the Increase Productivity with an Integrated Software Framework for Measurement and Automation white paper (linked below).

You can reduce the Blackfin design process by using the LabVIEW development environment to integrate measurements into the product design flow. For example, you can extend a debug system to integrate the video or audio signals for peripherals, or you can integrate VisualDSP++ automation to develop testing sequences for different DSP algorithms. With the tightly integrated framework of LabVIEW and NI hardware, you can quickly build systems that function exactly as you need.

See Also:
Increase Productivity with an Integrated Software Framework for Measurement and Automation

The Blackfin ADSP-BF537 ELVIS Connector

The Blackfin ADSP-BF537 EZ-KIT Lite ELVIS connector allows for direct connection to NI ELVIS workstations or NI data acquisition hardware to create real-time stimulus/response systems. In addition, the Blackfin ADSP-BF537 EZ-KIT Lite evaluation board allows you to use different signal types and signal paths in a system. Figure 2 shows a portion of the Blackfin ADSP-BF537 EZ-KIT Lite schematic that you use to configure a board.

Use the Function Generator Switch (SW8) to select the input source to the evaluation board’s audio amplifier (AMP_LEFT_IN, AMP_RIGHT_IN). The Function Generator Switch has the following switch options:

• The Blackfin ADSP-BF537 EZ-KIT Lite board includes a mini audio connector that is selectable through the LEFT_IN, RIGHT_IN pins.
• To access signals from a data acquisition device, such as a NI data acquisition board or function generator, select the signals DAC0, DAC1 that are connected to the Blackfin 537 ELVIS connector.
• To use the Blackfin ADSP-BF537 evaluation board with the NI ELVIS station, select the FUNC_OUT signal.

National Instruments can supply a special conversion board called the ELVIS_To_MIO Adapter (EMA) (Part Number 192400A-01) that directly converts the ADSP-BF537 ELVIS connector to a 68-pin NI data acquisition connector. Refer to Pin Names for ELIVS_ADI_MIO.xls for the pinout mapping of the EMA adapter board.

 

Creating Stimulus/Response Systems Using NI ELVIS

NI ELVIS, shown in Figure 3, is a LabVIEW-based design and prototype environment for university science and engineering laboratories. NI ELVIS consists of the following:

• LabVIEW-based virtual instruments (Figure 4)
• Multi-function data acquisition (DAQ) device
• Bench-top workstation (Figure 5)
• Prototype board

This four-part combination provides a ready-to-use suite of instruments required in most educational laboratories. NI ELVIS is ideal for academic course work ranging from lower-division classes to advanced project-based curriculum. Because the system relies on LabVIEW, NI ELVIS delivers the flexibility to provide complete data acquisition and prototyping capabilities. By using NI ELVIS in your DSP laboratories, you can provide students with a leading edge, virtual instrument-based education. Refer to the NI Elvis link below for more information about NI ELVIS.
The Blackfin ADSP-BF537 EZ-KIT Lite evaluation board connects directly to the NI ELVIS workstation. With ELVIS-based virtual instruments, you can measure:

• DSP I/O current
• DSP current
• DSP voltage

You also can:

• Stimulate the Blackfin ADSP-BF537 evaluation board with custom analog signals.
• Control the digital I/O LEDS on the Blackfin ADSP-BF537 board.
• Generate custom interrupts or timed events to and from the Blackfin processor.

For example, it is very easy to create complex analog waveforms using virtual instrumentation to stimulate the Blackfin evaluation board. With your own custom signal types, you are limitless in the real-time stimulus signal combinations.


Using flexible LabVIEW graphical programming and modular hardware, such as NI M-Series data acquisition hardware, scientists and engineers can deliver stimulus/response systems that exactly match the needs of the DSP device you are testing. The Blackfin ADSP-BF537 ELVIS connecter, along with the NI ELVIS to MIO Adapter (EMA), allows you to connect a Blackfin ADSP-BF537 EZ-KIT Lite evaluation board to NI data acquisition hardware.

Similar to NI ELVIS, you can directly connect the Blackfin ADSP-BF537 evaluation board to NI data acquisition hardware. With NI M-Series data acquisition hardware you can measure:

• DSP I/O current
• DSP current
• DSP voltage

You also can:

• Stimulate the Blackfin ADSP-BF537 evaluation board with complex analog signals.
• Generate custom interrupts or timed events to/from the Blackfin processor.

You use the same software to program NI data acquisition systems as NI ELVIS, so it also is very easy to create complex analog waveforms to stimulate the Blackfin evaluation board. With your own custom signal types, you are limitless in the real-time stimulus signal combinations. As another example, suppose you want to better understand the real-time DSP current consumption of a specific software algorithm. Using the Blackfin ADSP-BF537 evaluation board and virtual instrumentation hardware, you can develop DSP code to toggle a GPIO line at the beginning and end of a software algorithm. GPIO lines from the Blackfin ADSP-BF537 are directly accessible through the Blackfin ELVIS I/O connector, as well as real-time DSP current in the form of a shunt resistor voltage. With the knowledge of both algorithm timing and real-time current consumption, you can reduce coding challenges often encountered with low power designs.

Conclusion

The Blackfin ADSP-BF537 EZ-KIT Lite evaluation board is equipped with an I/O connector based on NI ELVIS to allow for direct connectivity to National Instruments ELVIS or data acquisition hardware.

NI ELVIS was designed to address both instructor and student needs. It provides an economical, highly customizable environment that students find easy to use. Because of its powerful software suite and easy serviceability, NI ELVIS is the ideal solution for both introductory and higher-level courses. By using NI ELVIS in your DSP laboratories, you are able to provide students with a leading edge, virtual instrument-based education.

NI data acquisition hardware and modular instruments integrated with the Blackfin ADSP-BF537 EZ-KIT Lite reduce the time to application and time to market. By linking real-time stimulus/response signals and direct power measurements, you can better understand application performance during designing and debugging.

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