[PDF] A 6809 single-board computer system for the control of behavioral

View - Download A 6809 single-board computer system for the control of behavioral

Previous PDF

Next PDF

BeltoviorhsearehMethods, Instrumenis,4Computers

1991,23 (4),513-522

-COMPUTERTECHNOLOGY

A6809single-boardcomputersystemfor

thecontrol ofbehavioralexperiments

JOHNM.HORNER

Colorado College, ColoradoSprings,Colorado

Acomputersystemconsistingof a 6809single-boardcomputerinconjunctionwithanIBM compatiblePersonalComputer(PC) isdescribedforthecontrolofbehavioralexperiments.The single-boardcomputeruses theC componentof ware)isoutlined withitscapabilitiesanddrawbacksnoted.

513With the advance

ofdigital computers came the promise of powerfulexperimentaldesigns and morethoroughdata collectionand analysis (Uttal,1968).Sadly,thispromise has notbornemuchfruit,partlybecausetheamount of technicalexpertiserequiredto build acomputersystem is extensive, and partly becausethe cost intimeand money to build acomputersystem from scratch isenormous.This blueprintfor arelativelyinexpensiveyetpowerfulcom putersystem for thecontrolofbehavioralexperiments. researcher'scontrol and analysis capabilities. The present system iscapable ofcontrolling,timing,andrecording system is based on the high-level language "C"and soft ware that does not assume anyparticularexperimentalap proach,theprogrammingofexperimentsand the anal ysis ofdata are left up to theexperimenter'scapabilities andimagination.Hence,thepresentsystem is apower ful and flexible tool forbehavioralresearch,yet it costs less thanothercomparablesystems.

Thesystemisbasedon a 6809ControlModule

(6809 CM)single-boardcomputerthat runs theexperi ment (seeFigure1). The 6809 CMcontrolsand senses The author would like tothankAlan Campbell for his help in the de sign and construction of the system described here-withouthis help this system would never have been developed. The author would also like to thankKen Steele and other anonymous reviewers for their com ments onearlier drafts of this paper. All three output circuits described herein were designed by Alan Campbell. The inputcircuitis based on a hybrid circuit thatincorporatesthe design features of Alan Campbell, John Hinson, Alliston Reid, Ken Steele, and myself. The data-storage technique described herein isbasedon a technique first devised by John Hinson. Any designerrorsin this article are theresponsibilityof the author. Theprojectwas supported by a generous grant from Colorado

College for faculty research

anddevelopment. Reprint requestsandother correspondenceshould beaddressed to John M.Homer,Psychology Department,ColoradoCollege,Colorado Springs, CO 80903 (e-mail:

JHORNER%CCNODE@VAXF.COLORAOO.EDU).

experimentalevents,such asstandardbehavioralelec tromechanicaldevices andmanipulanda,through a digi tal interface.

AnIBM-eompatible Personal Computer(PC)

servesas the"host"for the 6809CM.ThePCperforms the tasks ofcompiling andtransferringprograms(thatrun theexperiments)to the 6809 CM(i.e.,downloading) and storingandanalyzingdata from the 6809 CM(i.e.,up loading). The

PCand the 6809 CMcommunicatethrough

a serial(i.e.,RS-232) line. The Cprogramminglanguage serves for both theprogramming ofexperimentsand the analysis ofthe data from eachexperiment.

Thisdesignfollows thephilosophythat each 6809 CM

serves as astand-alonesystem forrunninga single ex periment. Thus, the system is simplifiedbecauseone com puter(6809 CM) runs oneexperiment.Hence,each

6809 CM is isolated from oneanotherin such a way that

failures in one do notproducefailuresinanother.This design has the added benefit that the

PCis left free to per

etc.)while the 6809 CM isrunningexperiments.This one-eomputer,one-experimentdesignis feasible because the cost ofeach 6809 CM isrelativelyinexpensivecom paredwithothermethods ofcontrollingexperiments, Althoughthe system issimpleas a whole, it is a com plexcollectionof parts thatrequiressomeassembly.The following sections of thispaperdescribeeachcomponent andexplainhow it functions aspartofthe system. Addi tionalinformationwill besuppliedby theauthoron request.

THESINGLE-BOARDCOMPUTER

The 6809 CMusedby this system is based on the Moto rola 6800 family ofchips and iscommerciallyproduced.

Thecentralprocessingunit(CPU)is thehybrid8/16-bit

6809chip,which is apowerfulmicroprocessorthat sup

yet isstraightforwardinoperation.

The6809represents

Copyright1991PsychonomicSociety,Inc.

514HORNER

6809CONTROLMODULE

INPUT

¢::::::lOUTPUT

DIGITALINTERFACE

Figure 1. A stylizedrepresentationof the present system. the acme in8/16-bitdesign-toimproveCPUperfor manceby asignificantamount,one would need to ex pandto alargerbitstructure.Becausebehavioralevents (i.e.,keypeck,hopperoperations)are fairlyimpreciseby computerstandards, an8/16-bitmicroprocessoris all that isnecessaryto run mostbehavioralexperiments.These facts,inconjunctionwith the

6809'suse innumerousin

dustrialandcommercialapplications (e.g.,GMEn gineCM),itsprovenperformancein manyresearchap plications(e.g.,Walter/Palya[1984]system),and its ex tensivesupportbyotherchipsin the6800family of microprocessorsandperipherals,make it the idealCPU forrunningbehavioralexperiments.

The6809 CM used by thepresentsystem iscommer

ciallyproducedby theWintekCorporationandconsists ofthe 6809CPU,56Kofmemory(RAM),aI-MHz clock,two RS-232serialports,and twoperipheralinter faceadaptor(PIA)chips(6821),whichhandleup to 32

TILcompatibleparallelinputand output lines inaddi

tion totheircontrollinglogic.The 6809 CM has its own on-boardmonitor/debugger(Fantom9), which aids in particular6809 CM waschosenoveranumber ofother systemsandmanufacturersfor the followingreasons: (1) Each 6809 CM isinexpensive;(2) each has a num berofstandardhardwarefeatures,suchasserial andpar allel ports andmemory;(3) thisproducthassoftwaresup port,whichincludesa Ccross-eompiler/assembler,an on-boardmonitor/debugger(Fantom9), and acommu nication package(Terminal Emulator);(4) the 6809 CMs comealreadyassembledon anindustry-standard4.5X

6.5in.circuitboardwith astandard44-pinconnector;

(5) there is extensivehardwaresupport for the 6809 CM, system;and (6) it isbasedon theMotorola6800family of8-bitmicroprocessors.

The6809CMscan beequippedwith anerasable,

debuggercalledFantom9,whichallows the6809CM to act as astand-alone computer-performinginteractive taskswith theoperator,such as runningprograms,debug gingsoftware,andtransferringdata.The 6809 CMdoesnot needFantom9 tofunction,becauseanexperiment (i.e.,computerprogram)can bepermanentlystored(i.e., facilitatesthe operator'sinteractionwith the6809CM, thisapproachlimitstheflexibilityofthesystemand is thereforenotadvised.

The 6809

CMissufficientto run thesystemdescribed

herein;however,themanufacturerdoessupplya num modules,whichallowsthe user theflexibilityto easily expandthesystem.Memorycan beexpandedto512K, and

I/Ocan beexpandedto 96 lines.Thebasicsystem

forrunningexperimentsis based on aminimalconfigu ration ofonly 8outputs,8 inputs, and 24Kofmemory.

Expansion

ofthebasicsystemwouldrequireadditional purchases and/oraminimumofprogrammingchanges.

The 6809

CPUchip, although it isthe"thing"thatruns

theexperiment,is not thecomponentthatmakesthe

6809 CMuseful.

The6809 CM has twoPIAs(6821) that

enable the

CPUtosenseandcontrolexperimentalevents.

The two PIAsallowfor up to 32separateeventsto be

handledconcurrently.This is farmorethan thestandard number ofeventsused invirtuallyanybehavioralexperi ment.Because ofvoltagedifferencesbetweencomputers and moststandardbehavioralapparatuses,it isnecessary toprovideadigitalinterfacebetweenthePIAsand the apparatus.The nextsectiondescribessuch aninterface.

THE DIGITALINTERFACE

The 6809 CMsensesandcontrolsexperimentalevents

control ofeventsin thebehavioralchamber(outputs)is performedvia adigitalinterfacebyturningon and off oneofthedigitalswitchesin oneofthe PIAchips.This in tumswitchesthepoweron andoffto anyelectrical orelectromechanicaldevice.Thetechnologyfor the con trol ofthesedevicesis wellestablishedand toonumer ous toreference(see Ratzlaff, 1987, for an excellent over view

1984, orWolfe,1982,for morecookbookapproaches);

6809 COMPUTER SYSTEM 515

110 VAC

HOPPER

+5 +5 180n
4.7K 6 6821
PIA MOC

PH?74075NIl'

U6 3031

NIl'3 180n
.005 200V
1---- 0 IK .1 200V
110
VAC

TCElYPE

ORSK3938

SK 5538

ORNTE 5608

12G

7407>--.....-..

6r----.,hDJ'+---oAC

MOCIN 5"Ie PH'! 6821
PIA +5 4.7K +5 IRon LAMP V6 3031

NIl'.J

AC

COMMON

+S V+

DCLOAD·

+5 180n
4.7K 6N/C 6821

PIA4N-33680

n

PH?7401

25
V6 N/C34 Figure 2.OutputcircuitsforthedJgitalinterfllCe.The74fY11sastandard1TLdeviceaDdl'UDSona+5 Vdepower source.PH?referstoanyoutputportonthe6821 PIAoftheCM6809(chipU6).FJaure2AshowsabiIh-current

found under.Triaclllnmostcatalop.)FIgure2CshowsacomparabledebJlb-c:urrentcircuit.(·Ifthe deloadIs1Dduc

tive, a diodelDllshouldbeplacedinparaJJeIwiththeloadLDI=IN4004 THR).)TheopdcaJJsoIator,4N-33,Is ratedat 30 V, andtheNPNtransistor,2N3055,Isratedat 15 A,althoughlower ampratInpwoulddoformostlI8e8.

516 HORNER

suffice it to say that anything that can becontrolledby an electrical switch can becontrolledby acomputerwith theappropriateinterface. To be appropriate, an interface must convert the voltage signal used by thecomputerto a voltage signal used by the electrical device, while providinga buffer between the two voltages. Although a number of circuits would sufficetoperform this function,Figures2A, 2B, and 2C show schematics for output circuits that have been used with this or simi lar systems.Figures2A and 2B show schematics for ac outputdigital devices. Both ac circuits use two simple chips,a TTL hexinverter(7407), and an optical isolator (MOe3031). The opticalisolatorallows various types ofcurrentsand devices to be used by the digital switches withoutmixing thecurrentand thus damaging the digital interface.

Figure2Aillustratesthe kind

ofcircuit used topower acelectromechanicaldevices that draw a lot ofcurrent, such as an ac grain hopper. A Quadrac is used to switch poweron and offto the device, as opposed to switching directlythrough the optical isolators.Figure2B shows how the opticalisolatorcan be used to switch a low currentdevicedirectly. Figure 2C illustratesa circuit used topowerany low-voltage de device, and is based on the same philosophy of design as the ac circuits. The number and kind of outputs used are left to the ex perimenter.In myexperiments,I rarely use more than eightoutputs; thus, I have never had to use more than one ofthe 6809CM'stwo PIA chips. Outputs are added

to the system byduplicatingtheappropriatecircuitsandconnecting thecircuitsto theappropriatePIA line and

electromechanicaldevice. Theregisteringofexperimentalevents (inputs) is per formed by the same PIA chip.Experimentalevent(i.e., keypecks, barpresses) produces changes in the state of the

PIA-viathe digitalinterface-whichthen signals the

CPU chip that an event hasoccurred.The input circuit incorporatesastraightforwarddigital pulseformerand signalconditioner (see Figure 3), whichallowsa relatively clean and consistent signal to be accepted by the PIA. Any other noise is filtered out by thesoftwareand istranspar ent to the user. The input circuit shown in Figure 3 is based on an "in terrupt"design philosophy. Aninterruptis a signal from a PIA to the 6809 CPU that an event hasoccurred.This causes the

CPUto stop what it is doing and take care of

(i.e.,service) the interrupt. An interrupt allows for events in the world to be detected much more reliably and ac curately than otherapproaches.Othermethods,such as polling, are lessefficientwith CPU time. Additional inputs can be added byduplicatingthe sig nalconditioning partof the circuit and chaining theQout puts from the 74121 into theinterruptcircuit's7486 (see

QlandQ3insert inFigure3). In thismanner,a number

of inputcircuits can be added to the hardware with a mini mum amount of digitalcircuitry. Puttingtogethera board with eight input and eight out putcircuits involves an expense of under $100 and a day's worth ofsoldering.This jobis well within the skills of lOOK Q3 +5 4 14 7474
..CB2 U6

Figure 3.Inputcircuit f\)r the digital interface. Both the CMOS 4050and theTIL7486 usestandard+S volts dc power

sources. PA? refers to any input port on the 6821 PIA of the 6809 CM (chip

U6).The 6821 ports CBI and CB2 make up

theinterrupthardwareof the 6821 PIA and work in conjunction with theinterruptcircuitryoutline in this figure and the

software described in the text. Theinterruptlogic shown in Figure 3 assumesthatno two events occur simultaneously.

If

simultaneous events are possible within anexperimentalframework,then a single multiple NOR gate (7430) maybe used

in place of the 7486 chain. All unused 4050 inputs shouldbetied toVee(S+).quotesdbs_dbs5.pdfusesText_9

[PDF] 6809 disassembler

[PDF] 6809 indexed mode

[PDF] 6809 instruction set pdf

[PDF] 6809 instructions

[PDF] 6809 microcode

[PDF] 6809 pinout

[PDF] 6809 processor datasheet

[PDF] 6809 programming manual

[PDF] 6809 pshu

[PDF] 6809e datasheet

[PDF] 687 area code

[PDF] 68hc11 example code

[PDF] 68hc11 instruction set

[PDF] 69 co defendants

[PDF] 69 cours de verdun oyonnax