6lAkit-BASICStamp2SX : BASICStamp2SXActivitykit
4.3Sounddriver
AX-2SXboardprovidesa100mW8Wspeaker andconnectwithP12ofi-Stamp.i-
StampcanouttheaudiosignalcoupleviaC2;10mF capacitortodrivethisspeaker.This
circuitdemonstratethei-Stamp’sperformanceaboutdrivingasmall speakewithout
externalamplifier circuit
4.44-Inputswitches
AtP8toP11are assignedtoInputports.Theyareconnected4ofpush-button
switchesandconnected4pull-upresistortodefinelogic“HIGH”innormalstate.Ifany
swithispressed, thatportwill beconnectedtoground. Logic“0” will appliedatthatport.
i-Stampcanreadport’statuswithprogramming.
Addition atP8toP11 haslimit-currentresistor220W(R9toR13) forprotectingi-Stamp’s
port.Normallyi-Stamp’sportcanconnecttoGrounddirectlybutmustsettoINPUTonly.
TheR9toR13 are usedtoprotectportdestroyincasesettinganyporttooutputand
switchispressed.Ifnotprotected,i-Stamp’sportwill bedestroy.
4.5Relay driver
P13 ofi-StampisconnectedwithULN2003 input(pin7).OutputofULN2003 (pin10)
isconnectedwith12Vrelay. i-Stampcanactivetherelayoperation withsendlogic“1” to
pin7ofULN2003.ULN2003 will invertlogictoactivaterelay.Relay’scoil havecurrent
draw.LED9lightsuptoindicatestheoperation andrelaycontactwill switchfromNCto
NO.Relaycontactratingis220Vac5Aandsuitabletodrive600Welectricload.User can
connecttheelectricapplianceloadtocontrolledbyi-Stamp.
4.6LDRcircuit
Onefeature ofi-Stampisthesimpleanalogsignalprocessingwithspecialcommand;
RCTIME.ThiscommandconceptisRCtimeconstantoperation.InAX-2SXboard,useLDR
(LightDependentResistor)and0.1uFcapacitor.They are connectedtoP14 ofi-Stamp.
R14 resistorisconnectedwithP14 inseriesfor2purposes.OneisassistancetheRC
operation start.Another function iscurrentlimitation fromreversecurrentofcapacitor
rechageing.
4.7Serialinterface port
AX-2SXboardassignP15 ofi-Stamptoserialcommunication porttoextension.The
externaldevicethatconnectatthisportmusthaveserialcommunication suchasthe
SerialLCD,SerialkeypadorSerialRealtimeclockmodule.Serialinterfaceconnectoruse
3-pinsheader.Theassignmentportfromleftis+5V,P15 orsignalandGround.Sameany
previousport,P15 hasacurrent-limitresistorforprotection.
