VisSim/Embedded Controls Developer - IEEE Xplore

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Oct 1, 2007 - VisSim/Embedded Controls Developer. Visual Solutions, Inc., (VSI), head- quartered in Westford, Massa- chusetts, is the creator of. VisSim ...
PRODUCT SPOTLIGHT

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VisSim/Embedded Controls Developer

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n this issue of IEEE Control Systems Magazine, we focus on VisSim/ Embedded Controls Developer, which enables the development of embedded control systems code for the Texas Instruments’ MSP430 microprocessor family. VisSim/ECD is produced and marketed by Visual Solutions, Inc. Please contact me with your suggestions for future Product Spotlight columns. All products listed in this column are provided as a reader service and do not constitute an endorsement by the IEEE or CSS. Vikram Kapila [email protected]

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isual Solutions, Inc., (VSI), headquartered in Westford, Massachusetts, is the creator of VisSim, a block-diagram programming environment for dynamic-system simulation and embedded control system development. This product spotlight features the new VisSim/ Embedded Controls Developer (ECD), which supports the Texas Instruments’ (TI) 16-bit MSP430 lowpower microprocessor line. IEEE Control Systems Magazine thanks Pete Darnell, founder and CEO of VSI, for speaking with us.

Q. What is VisSim/ECD for MSP430 and what does it do? Pete: VisSim/ECD for MSP430 provides graphical embedded controls development capability for the TI’s MSP430 microprocessor family. Digital Object Identifier 10.1109/MCS.2007.903681

For the on-chip peripherals of the MSP430, VisSim/ECD generates efficient code that can fit within the limited on-chip memory resources of the MSP430. The ability to produce small memory footprint target files for the MSP430 microprocessor line is challenging because the MSP430 family has almost 100 different members, each of which has a combination of flash, RAM, peripherals, and a different price point. The smallest and least expensive MSP430 microprocessor, which costs about US$.50, has 1 KB flash, 128 B RAM, ten general purpose inputs and outputs (GPIO), two comparators, and two pulse-widthmodulated (PWM) outputs. The largest MSP430 microprocessor, which costs about US$10, has 120 KB flash, 4 KB RAM, 80 GPIO, inter-integrated circuit (I 2 C) bus, two serial ports, serial peripheral interface (SPI), 12 12-bit analog-to-digital converter (ADC) channels, two 12-bit digital-toanalog converters (DAC), three op-

VisSim dialog box for configuring the MSP430 chip. This tool enables the selection of clock rates, main control interrupt source, low-power level, and LCD segment driver. Chip peripherals such as ADC, DAC, I2 C, and serial port are configured by similar dialog boxes. The VisSim code generator produces inline C code to initialize and drive on-chip peripherals with minimal overhead.

amps, direct memory access (DMA), and 160 liquid crystal display (LCD) segments.

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What motivated the creation of VisSim/ECD for MSP430, and how was it developed? Pete: A few years ago when we participated in TI’s control-system seminar to promote our C2000 target support, we kept hearing about a new low-cost, low-power chip set called the MSP430. Our market research revealed that MSP430 revenues were growing at a staggering 65% a year. Moreover, the increasing demand for lower energyconsuming products and the growing popularity of wireless RF and batterypowered applications assured us that the MSP430 would sustain a strong growth rate for many years to come. Around that time we began hearing from potential customers who were seeking a graphical method to program the MSP430 chip sets. We decided it was an excellent opportunity to develop VisSim/ECD for MSP430 to meet the market demand.

Q. What is innovative about VisSim/ECD for MSP430? Pete: First of all, the MSP430 chip set is a clever product from TI. It was originally architected to use minimum power, and it is designed to practically shut itself down after servicing an interrupt and wake up instantly on occurrence of the next interrupt. In active processing mode, it uses as little as 200 μA, while in sleep mode, it uses less than 500 nA. The MSP430 chip set has on-chip digitally controlled oscillators, timers, and a variety of other peripherals so that no additional parts are required.

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event capture, and lowThese peripherals make power modes. The I 2 C the chip set useful in any application where low cost and serial drivers have and low power usage is user-selectable queue important. The problem is lengths and are interrupt that it takes time to figure driven. Care has been out how to activate and taken to keep driver make use of all these feaoverhead to a minimum. tures. We have worked Inline code is generated closely with TI to provide where possible since simple configuration VisSim/ECD-generated C-code can be compiled and downloaded to the peripheral support is dialogs (see Figure 1) and Texas Instruments' MSP430 microprocessor. The code from this VisSim useless if it does not fit an extensive MSP430 block diagram reads and filters analog values and then sends the result to the into the limited flash and set to create control appli- serial port. RAM of the MSP430 part. cations that use on-chip capabilities. For A measure of performance is the effiexample, a diagram to read an analog Q.What are the implications of Vis- ciency of the code generator. Since input, perform digital filtering, and Sim/ECD for MSP430 for control efficiency is hard to quantify, memory write the result to a serial or I2 C port engineers? usage is given for two sample cases. Pete: Control engineers who are takes as little as six blocks (see Figure 2). » A minimal diagram to blink an not experts in C or assembler can LED takes 324-B flash memory develop applications directly using a and 64-B RAM. Q. Who are the end users of VisSim/ECD for MSP430 and how block-diagram programming environ» A PI controller with quadrature ment. They can perform model-based might they use it? encoder input, 16-bit analog Pete: End users include embedded development by simulating fixedinput as setpoint, and PWM application designers who are cost or point control algorithms offline before output uses 990-B flash and power conscious, but not experts in generating code. 94-B RAM. MSP430 architecture, as well as current Q. Who are the early adopters of MSP430 users who wish to improve Q. What are the key specifications VisSim/ECD for MSP430? their programming efficiency in C or of VisSim/ECD for MSP430? Pete: Early adopters are control assembler. Typical applications are Pete: VisSim/ECD for MSP430 has engineers, professors, and students battery-powered wireless RF-based a comprehensive set of blocks to gen- considering a 16-bit micro for their control, LCD user interfaces, remote erate code for on-chip peripherals, next project. Anyone involved with sensing, autonomous vehicles, bio- including 10-bit, 12-bit, and 16-bit battery-powered, handheld devices, medical monitoring, wireless metering, ADC, 12-bit DAC, op-amps, PWM, mobile autonomous devices, or lookand in touch-sensed battery-powered I 2 C, serial, seven- and 14-segment ing to lower the power budget of an entertainment devices. LCD, PWM, quadrature encoder, existing design may wish to consider

Extreme Avoidance

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herefore a discussion on engineering cybernetics should cover reasonably well all aspects of the science expected to have engineering applications and, in particular, should not avoid a topic for the mere reason of mathematical difficulties. This is all the more true when one realizes that the mathematical difficulties of any subject are usually quite artificial. With a little reinterpretation, the matter could generally be brought down to the level of a research engineer. The mathematical level of this book is then that of a student who has had a course in elements of mathematical analysis. Knowledge of complex integration, variational calculus, and ordinary differential equations forms the pre-requisite for the study. On the other hand, no rigorous and elegant mathematical argument is introduced if a heuristic discussion suffices. Hence to the practicing electronics specialist, the treatment here must appear to be excessively “long-hair,” but to a mathematician interested in this field, the treatment here may as well appear to be amateurish. If indeed these are the only criticisms, then, with all due respect to them, the author shall feel that he has not failed in what he aimed to do. — From H. S. Tsien, Engineering Cybernetics, McGraw-Hill Book Company, Inc., New York 1954, page viii.

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phone, buzzer, headphone using VisSim to accelerate the jack, capacitive touch sensidesign process. If you’re looktive area, serial transceiver, ing to do digital power or ADC, DAC, battery pack, and motor control, then the TI both an MSP430FG4619 and C2000 is the best part since it an MSP430F2013 microruns faster and has better processor. The FG4619 and peripherals for that technology. F2013 are connected and can VisSim supports that chip set communicate through I 2 C. as well. We have seen cases where The board also has a socket to the adoption of VisSim can be accept a Chipcon RF module useful in projects that are far that communicates with the along. Many projects have a F4619 using SPI. This evaluacontrol engineer who works tion board is great for experiwith a programmer or promenters or university level gramming staff. Recently we MSP430 Experimenter’s board from Texas Instruments. The courses in embedded syshad a case where a control board has two separately programmable MSP430s, the tems or robotics. The boards engineer at a global service FG4618 with 116-KB flash/8-KB RAM, and the F2013 with 2- run from US$50 to US$100. provider for energy compa- KB flash/128-B RAM. Both devices are programmable using Another USB “thumb drive” nies had been working with a the VisSim block-diagram language. evaluation board is priced at programmer for a year trying US$20, so cost is not really an to get a large electric motor to spin Pete: Commercial pricing of issue in getting started with this properly. Each engineer was pointing VisSim/ECD for MSP430 starts at technology. at the other as the reason for failure. US$3495. Academic pricing starts at The control engineer downloaded a US$350 for a single seat, with steep For more information, contact: trial version of VisSim/ECD and had classroom discounts. Jim Webb, Sales Director the motor spinning within a week. On the hardware side, TI has Visual Solutions Inc. created MSP430 evaluation boards Voice: 978-392-0100 Q. What is the cost of VisSim/ECD (Figure 3) with push buttons, LEDs, a Email: [email protected] seven-segment LCD display, micro- URL: http://www.vissol.com/ for MSP430?

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IN MEMORIAM

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present results that were not rigorously stated and proved. On at least one occasion, he withdrew a paper that had already been accepted on the grounds that he felt that the results were not sufficiently important. As a research advisor for doctoral students, he motivated his students to meet his high standards and continually extend their horizons. As a classroom teacher, he was simply superb—direct, clear, and demanding, always at an appropriate student level. Many of his classroom students volunteered that he was the “best teacher they ever had.” Prof. Root was the organizer and first chairman of the graduate program in computer, information, and control engineering at the University of Michigan. He treated colleagues and students alike, demanding from them integrity, high standards, preci-

sion in research, and a little bit of humility. He did this with his easy manner and good humor. Bill married Harriett Jean Johnson in 1940; she preceded him in death on April 23, 1998. Bill and Harriett leave two children, daughter Wendy E. (Allan) Cate of Los Angeles and William L. Root, Jr., of Ann Arbor, as well as eight grandchildren and one great-grandchild. Bill’s father, grandfather, and uncles were principals in the Root Casket Company of Des Moines, Iowa, a small firm that made and sold redwood burial caskets. He spent many summers as a teenager working various jobs at the casket manufacturing plant. He began lifting weights as a teenager and stayed an avid weightlifter all his life. He specialized in power lifts, specifically, the deadlift

and squat. His best deadlift was 515 pounds. He made regular trips to the gym into his 80s and maintained an active gym membership until 2006. He also began golfing and swimming as a teenager. He still had a set of wood shaft golf clubs. He greatly enjoyed classical music and sang baritone in college quartets and later in choirs. In retirement, his reading interests expanded to include the history of science, philosophy, neuroscience, and modern physics. He had a dry, penetrating sense of humor, and owned and enjoyed cartoon collections from the New Yorker as well as most of Charles Addams’ work. Bill will be missed by all those who had the good fortune to know him. Based on material from Frederick Beutler, Stuart Schwartz, and Bill Root, Jr.

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