generate barcode image vb.net TtMEnO in Software

Encoder PDF 417 in Software TtMEnO

,:a*{!ii!niFiigi usinsIMERo (Proglam btinks LEDS andDo]ailernalety rwo and [D1 blinks thirdLED[D2]lor onesecond andonesecond a ON OFFas conlrotted the by interrupl signal)

j 'ed'6noj\

OPTION F-EG=%10000101 ; page 48 of daLasheeL pu ups o orJ! B ; bit 5=0 selects tiner node i biL 2=L j ; biL 1=0 ] seLs Tinero prescala ro 64 ; bit 0=1 ] IiCTCON=%10100000 ; : ; ; ; j ; bit 7=1 Enables alL umasked intefuupts b r 'EraoaqTim- 0 ov-rfow - -e--p brt 2 flag wiLl be ser on inieriupt and has lo be cLeared in Lhe inlerrupt rouLine rt is set clear ar srar! nis v" i"ble co- : n r l - D a u s dr S o o p this variable counLs the 61 intefupt

IRISD - %11110100 ; sets lhe 3 output pins in the D porr P O R T D= % 0 0 0 0 0 0 0 0 ; sets all pins row in the D porr aEtA=0 ON IIITERR[IPT Go:rO INTROUIIAIE ; this Line needs to be early in ; lhe progran, in dy case, before the routine is ca11edMATN']OOP: IFPORIDI=0THEN PORIDI = 1 POR!Do = 0

EI,SE PORTDI - 0 PORIDo - 1 ENDIF lOR tl,PEA = 1 TO 300 : PAUSEUS100 NEXI AI,PIIA GCIIIOIIAII\ILOOP

/i q -

and (Program iwo blinks LEDS andD0]allernalelv UsinsTlMERo [D1 a:!!4ff!!il{lg* bythe ones cond OFFas conlrolled ON blinks thrrdLED[D2]foronesecond and a (Contlnued) inlerrupl signal) IMIROUTINE: ; bhis infornation ; odLv' ls used bv Lhe conpiler

BETA=BETA+1 IF BETA< 51 TIlriN ENDMITERRUPT one second has noL vet passed ; BEEA = 0 ; loop lurns D3 on and off everv tF PoRTD3 = I IHEN ; inlerrupi PORTD3= 0 ; 61 tines through the inter:rupt routine EISE ; ThaL is about one second per fulL cvcle = 1 PORED3 ENDIF t ETIDTNIIERRUPT tN!coN2 = 0 ; clears the inlerrupt flaq, REAU!@ ; -esua h6 ma:- o oo dn NUSTbTACKCT ENAS!,E ; DISABLE ANd ENABLE routine ; the interrup! END ; end prograrn and Make your predictions then Try changing the 3 low bits in OPTION-REG to seehow they affect tbe operntion of the interruPt In Program62, Timer0 is runningfree and providing an interruptevery time its 8 bil counterovedows from FF to 00 The prescalaris setto 64 so we get the interrupt "lntRoutlne" routine, where we after 64 of thesecyclesWhen this happens, jump to the we make surethat 61 intetrupts have taken place,and if they have, we changethc sfate of an LED andretum to the placewherethe interupl took place(It happensthat it takes approximately 61 inteffupts to equal one secondin this routine with a processorrun ning at 4 MHz This could be relined by trial ard error after the initial calculation ) "IntRoutine" routine, but the Note that the interrupt is disabled while we are in the we that is ireerunningcounter still runningtowad its nextoverflowmeaning whatever goingto missthe nextinterif alohasto get donein lessthan 1/61seconds we arenot to rupt, unlesswe make someother arrangements count all the interupts (with an inlernal subroutine or someother scheme)It can becomequite complicated if a lot needs to be done, so we will not worry about it here Before going any further,let's take a closerlook at the OPTION-REG and the INTCON (intenupt control) registerTheseare 8_bitregisterswitb the 8 bits ofeach regas isterassigned follows: OPTION-REG the option register: the Bit 7 RBPUNol ofinterestto us at thistime(This bit enables po( B pull ups-) Bit 6 INTEDG Not of interest to us at this time (The intefiupt edge select bil on, detemineswhich edgethe interupt will be selected rising [1] or falling [0]) Eitheroneworksfor us

Bit 5 T0CS,Timer0clock select Selects bit which clockwjll be used I = Transition on TOCKI pin 0 = Internalinstruction cycleclock (CLKOUT) We will usethis, thc oscillator-Seebit 4 description Bit 4 TOSE,sourceedge selectbit Detemines when the counter will increment I = Increment on high-tolow transitior of TOCKI pin of 0 = lncrement low-to-hightransition TOCKI pin on piII toBir 3 PSA,prescalar assignment Decides what thepresca]ar applies I = SelectwatchdoCtimer (WDT) 0 = SelectTimero 'rill be usingthis We Bits 2, 1, and 0 define the prescalarvalue for the timer As mentioned edrlier, fie prescalar be associated timer (WDT) but not can with Timeroor with the watchdog both Note that the scaliflg for the wDT is half the va]ue for Timero for the samethree