OCTOBER 2007 « IEEE CONTROL SYSTEMS MAGAZINE 131

P R O D U C T S P O T L I G H T «

VisSim/Embedded Controls Developer

V isual Solutions, Inc., (VSI), head-quartered in Westford, Massa-chusetts, is the creator of

VisSim, a block-diagram program-ming environment for dynamic-sys-tem simulation and embedded controlsystem development. This productspotlight features the new VisSim/Embedded Controls Developer(ECD), which supports the TexasInstruments’ (TI) 16-bit MSP430 low-power microprocessor line. IEEE Con-trol Systems Magazine thanks PeteDarnell, founder and CEO of VSI, forspeaking with us.

Q. What is VisSim/ECD for MSP430and what does it do?

Pete: VisSim/ECD for MSP430provides graphical embedded con-trols development capability for theTI’s MSP430 microprocessor family.

For the on-chip peripherals of theMSP430, VisSim/ECD generates effi-cient code that can fit within the limit-ed on-chip memory resources of theMSP430. The ability to produce smallmemory footprint target files for theMSP430 microprocessor line is chal-lenging because the MSP430 familyhas almost 100 different members,each of which has a combination offlash, RAM, peripherals, and a differ-ent price point. The smallest and leastexpensive MSP430 microprocessor,which costs about US$.50, has 1 KBflash, 128 B RAM, ten general purposeinputs and outputs (GPIO), twocomparators, and two pulse-width-modulated (PWM) outputs. Thelargest MSP430 microprocessor,which costs about US$10, has 120 KBflash, 4 KB RAM, 80 GPIO, inter-inte-grated circuit (I2C) bus, two serialports, serial peripheral interface (SPI),12 12-bit analog-to-digital converter(ADC) channels, two 12-bit digital-to-analog converters (DAC), three op-

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

Q. What motivated the creation ofVisSim/ECD for MSP430, and howwas it developed?

Pete: A few years ago when we par-ticipated in TI’s control-system semi-nar to promote our C2000 targetsupport, we kept hearing about a newlow-cost, low-power chip set called theMSP430. Our market research revealedthat MSP430 revenues were growing ata staggering 65% a year. Moreover, theincreasing demand for lower energy-consuming products and the growingpopularity of wireless RF and battery-powered applications assured us thatthe MSP430 would sustain a stronggrowth rate for many years to come.Around that time we began hearingfrom potential customers who wereseeking a graphical method to pro-gram the MSP430 chip sets. We decid-ed it was an excellent opportunity todevelop VisSim/ECD for MSP430 tomeet the market demand.

Q. What is innovative about Vis-Sim/ECD for MSP430?

Pete: First of all, the MSP430 chipset is a clever product from TI. It wasoriginally architected to use minimumpower, and it is designed to practical-ly shut itself down after servicing aninterrupt and wake up instantly onoccurrence of the next interrupt. Inactive processing mode, it uses as lit-tle as 200 μA, while in sleep mode, ituses less than 500 nA.

The MSP430 chip set has on-chipdigitally controlled oscillators, timers,and a variety of other peripherals sothat no additional parts are required.

In this issue of IEEE Control Systems

Magazine, we focus on VisSim/

Embedded Controls Developer, which

enables the development of embed-

ded control systems code for the

Texas Instruments’ MSP430 micro-

processor family. VisSim/ECD is pro-

duced and marketed by Visual

Solutions, Inc.

Please contact me with your sug-

gestions for future Product Spotlight

columns. All products listed in this

column are provided as a reader ser-

vice and do not constitute an

endorsement by the IEEE or CSS.

Vikram Kapila

vkapila@poly.edu

Digital Object Identifier 10.1109/MCS.2007.903681

VisSim dialog box for configuring the

MSP430 chip. This tool enables the selec-

tion of clock rates, main control interrupt

source, low-power level, and LCD segment

driver. Chip peripherals such as ADC, DAC,

I2C, 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.

132 IEEE CONTROL SYSTEMS MAGAZINE » OCTOBER 2007

These peripherals makethe chip set useful in anyapplication where low costand low power usage isimportant. The problem isthat it takes time to figureout how to activate andmake use of all these fea-tures. We have workedclosely with TI to providesimple configurationdialogs (see Figure 1) andan extensive MSP430 blockset to create control appli-cations that use on-chip capabilities. Forexample, a diagram to read an analoginput, perform digital filtering, andwrite the result to a serial or I2C porttakes as little as six blocks (see Figure 2).

Q. Who are the end users of Vis-Sim/ECD for MSP430 and howmight they use it?

Pete: End users include embeddedapplication designers who are cost orpower conscious, but not experts inMSP430 architecture, as well as currentMSP430 users who wish to improvetheir programming efficiency in C orassembler. Typical applications arebattery-powered wireless RF-basedcontrol, LCD user interfaces, remotesensing, autonomous vehicles, bio-medical monitoring, wireless metering,and in touch-sensed battery-poweredentertainment devices.

Q.What are the implications of Vis-Sim/ECD for MSP430 for controlengineers?

Pete: Control engineers who arenot experts in C or assembler candevelop applications directly using ablock-diagram programming environ-ment. They can perform model-baseddevelopment by simulating fixed-point control algorithms offline beforegenerating code.

Q. What are the key specificationsof VisSim/ECD for MSP430?

Pete: VisSim/ECD for MSP430 hasa comprehensive set of blocks to gen-erate code for on-chip peripherals,including 10-bit, 12-bit, and 16-bitADC, 12-bit DAC, op-amps, PWM,I2 C, serial, seven- and 14-segmentLCD, PWM, quadrature encoder,

event capture, and low-power modes. The I2 Cand serial drivers haveuser-selectable queuelengths and are interruptdriven. Care has beentaken to keep driveroverhead to a minimum.Inline code is generatedwhere possible sinceperipheral support isuseless if it does not fitinto the limited flash andRAM of the MSP430 part.

A measure of performance is the effi-ciency of the code generator. Sinceefficiency is hard to quantify, memoryusage is given for two sample cases.

» A minimal diagram to blink anLED takes 324-B flash memoryand 64-B RAM.

» A PI controller with quadratureencoder input, 16-bit analoginput as setpoint, and PWMoutput uses 990-B flash and 94-B RAM.

Q. Who are the early adopters ofVisSim/ECD for MSP430?

Pete: Early adopters are controlengineers, professors, and studentsconsidering a 16-bit micro for theirnext project. Anyone involved withbattery-powered, handheld devices,mobile autonomous devices, or look-ing to lower the power budget of anexisting design may wish to consider

VisSim/ECD-generated C-code can be compiled and downloaded to the

Texas Instruments' MSP430 microprocessor. The code from this VisSim

diagram reads and filters analog values and then sends the result to the

serial port.

Extreme Avoidance

Therefore a discussion on engineering cybernetics should cover reasonably well all aspects of the scienceexpected 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 anysubject are usually quite artificial. With a little reinterpretation, the matter could generally be brought down tothe level of a research engineer. The mathematical level of this book is then that of a student who has had acourse in elements of mathematical analysis. Knowledge of complex integration, variational calculus, andordinary differential equations forms the pre-requisite for the study. On the other hand, no rigorous andelegant mathematical argument is introduced if a heuristic discussion suffices. Hence to the practicingelectronics specialist, the treatment here must appear to be excessively “long-hair,” but to a mathematicianinterested in this field, the treatment here may as well appear to be amateurish. If indeed these are the onlycriticisms, 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.

present results that were not rigorouslystated and proved. On at least oneoccasion, he withdrew a paper that hadalready been accepted on the groundsthat he felt that the results were not suf-ficiently important.

As a research advisor for doctoralstudents, he motivated his students tomeet his high standards and continuallyextend their horizons. As a classroomteacher, he was simply superb—direct,clear, and demanding, always at anappropriate student level. Many of hisclassroom students volunteered that hewas the “best teacher they ever had.”

Prof. Root was the organizer andfirst chairman of the graduate pro-gram in computer, information, andcontrol engineering at the Universityof Michigan. He treated colleaguesand students alike, demanding fromthem integrity, high standards, preci-

sion in research, and a little bit ofhumility. He did this with his easymanner and good humor.

Bill married Harriett Jean Johnsonin 1940; she preceded him in death onApril 23, 1998. Bill and Harriett leavetwo children, daughter Wendy E.(Allan) Cate of Los Angeles andWilliam L. Root, Jr., of Ann Arbor, aswell as eight grandchildren and onegreat-grandchild.

Bill’s father, grandfather, and uncleswere principals in the Root CasketCompany of Des Moines, Iowa, a smallfirm that made and sold redwood bur-ial caskets. He spent many summers asa teenager working various jobs at thecasket manufacturing plant.

He began lifting weights as ateenager and stayed an avid weight-lifter all his life. He specialized inpower lifts, specifically, the deadlift

and squat. His best deadlift was 515pounds. He made regular trips to thegym into his 80s and maintained anactive gym membership until 2006.

He also began golfing and swim-ming as a teenager. He still had aset of wood shaft golf clubs. Hegreatly enjoyed classical music andsang baritone in college quartetsand later in choirs. In retirement,his reading interests expanded toinclude the history of science, phi-losophy, neuroscience, and modernphysics. He had a dry, penetratingsense of humor, and owned andenjoyed cartoon collections fromthe New Yorker as well as most ofCharles Addams’ work.

Bill will be missed by all those whohad the good fortune to know him.

Based on material from Frederick Beutler,Stuart Schwartz, and Bill Root, Jr.

OCTOBER 2007 « IEEE CONTROL SYSTEMS MAGAZINE 133

using VisSim to accelerate thedesign process. If you’re look-ing to do digital power ormotor control, then the TIC2000 is the best part since itruns faster and has betterperipherals for that technology.VisSim supports that chip setas well.

We have seen cases wherethe adoption of VisSim can beuseful in projects that are faralong. Many projects have acontrol engineer who workswith a programmer or pro-gramming staff. Recently wehad a case where a controlengineer at a global serviceprovider for energy compa-nies had been working with aprogrammer for a year tryingto get a large electric motor to spinproperly. Each engineer was pointingat the other as the reason for failure.The control engineer downloaded atrial version of VisSim/ECD and hadthe motor spinning within a week.

Q. What is the cost of VisSim/ECDfor MSP430?

Pete: Commercial pricing ofVisSim/ECD for MSP430 starts atUS$3495. Academic pricing starts atUS$350 for a single seat, with steepclassroom discounts.

On the hardware side, TI hascreated MSP430 evaluation boards(Figure 3) with push buttons, LEDs, aseven-segment LCD display, micro-

phone, buzzer, headphonejack, capacitive touch sensi-tive area, serial transceiver,ADC, DAC, battery pack, andboth an MSP430FG4619 andan MSP430F2013 micro-processor. The FG4619 andF2013 are connected and cancommunicate through I2 C.The board also has a socket toaccept a Chipcon RF modulethat communicates with theF4619 using SPI. This evalua-tion board is great for experi-menters or university levelcourses in embedded sys-tems or robotics. The boardsrun from US$50 to US$100.Another USB “thumb drive”evaluation board is priced atUS$20, so cost is not really an

issue in getting started with thistechnology.

For more information, contact: Jim Webb, Sales DirectorVisual Solutions Inc.Voice: 978-392-0100Email: jim.webb@vissol.comURL: http://www.vissol.com/

MSP430 Experimenter’s board from Texas Instruments. The

board has two separately programmable MSP430s, the

FG4618 with 116-KB flash/8-KB RAM, and the F2013 with 2-

KB flash/128-B RAM. Both devices are programmable using

the VisSim block-diagram language.

» I N M E M O R I A M (continued from page 130)