5
Micro-controller
MINI-MAX/51-C2 hasan ATMELAT89C51ED2 micro-controller(U2).Micro-controllerportsand power
linesareprovided on a20-pinexpansion busforinterfacing toperipheralsand otherexternalcircuits.
AT89C51ED2 has4portsthat areavailableon the 8051 familyofmicro-controllers: P0…P3.
P0hasopen collectoroutputsthatareavailableon the LCD connectorwith4.7Kpull-up (RB1). P1and
P2aregeneral-purposebi-directionalinput/outputports.Port2isavailableon the keypad connector.
P1and P3areavailableon the expansion connector.P3pinscan eitherbe used asgeneral-purpose
input/outputpinsorhavespecialpurposessuchasasynchronousserialport, interruptinputsand timer
inputs.
Moreinformation on the AT89C51ED2 micro-controllercan be obtained fromATMELweb siteat
http://www.atmel.com.
SecondaryMicro-controller
MINI-MAX/51-C2 hasaMicrochipPIC16F818 micro-controllertoselectan In-circuitProgramming
mode orRun mode ofthe mainFlashmicro-controller.When aRun mode isused,PIC16F818 works
asan I2C slaveperipheraldeviceand can provide 5-channel10-bitADC using the 4.096Vinternalor
an externalvoltage referencesource.
In-SystemProgramming
AT89C51ED2 micro-controllercan be re-programmed remotelyoverthe RS-232 interfaceusing a
second micro-controlleron the board(PIC16F818 ).The in-circuitprogramming featuresimplifies
programdevelopmenton the boardsincedownloading programsfromahostPCtakesonlyfew
seconds. Userprogramscan alsobe debugged overthe serialport.
8051/52,BASCOM51,SDCC developmentsystemsbasedon Micro-IDEIntegratedDevelopment
EnvironmentfromBiPOMElectronics,fullysupportIn-System Programming and debugging on
theMINI-MAX/51-C2 using theserial port.
The on-chipDownloadableFlashof AT89C51ED2 allowsthe programmemory tobe reprogrammed in-
systemthrough RS-232 serialinterface.
The boardoperatesinthe twomodes:
1-RUN mode
2-PROGRAM mode
Run mode isastandardmode when AT89C51ED2 isrunning itsownprogram.
Programmode isaspecialmode when the hardwareconditionsduring the resetpulseforcesthe on-
chipboot loaderexecution.
PCchangesthe boardmode through the RS-232 serialinterfacebyausing ofRTSline.
PIC16F818 ispolling thisline permanentlyand ifthe signalchangesthe levelthen PIC16F818
switchesthe boardmode.
EEPROM
MINI-MAX/51-C2 usesa24C04 (U3)512 byteElectricallyErasableProgrammableRead-Only-Memory
(EEPROM).TypicallythisEEPROMisused forstoring calibration valuesforsensors,customer
identification,serialnumberand otherparameters.ThisEEPROMison asocketand can easilybe
replaced withhighercapacityEEPROM’s(up to128 Kilobytes).
