Cirrus-logic AN88 Manual de usuario descargar pdf (Pagina 12)

AN88

12 AN88Rev2

;*************************************************************************************

;* Routine - delay

;* Input - Count in register A

;* Output - none

;* This subroutine delays by using count from register W. The PIC16F84

;* development board uses a 10 MHz clock (E = 2.5 MHz), thus each cycle is

;* 400 nS. This delay is approximately equivalent to

;* (400ns)*(1545)*(count value), (a count of 720 provides a 445ms delay).

;*************************************************************************************

delay MOVWFCOUNT ; Put the delay count into COUNT

outlp CLRF TEMP ; TEMP used as inner loop count

innlp NOP ; 1 cycle

NOP ; 1 cycle

DECFSZ TEMP,1 ; FF-FE, FE-FD, ....1-0 256 loops

; 10 cycles*256*500ns=1.28 ms

goto innlp ; If count not done repeat loop

DECFSZ COUNT,1 ; Countdown the accumulator

goto outlp ; 2569 cycles*500ns*A

RETURN ; Exit subroutine

;*************************************************************************************

;* Interrupt Vectors

;*************************************************************************************

NOT_USED RETFIE

ORG 0x04 ; Originate Interrupt Vector here

goto NOT_USED ; No Interrupts Enabled

end ; End Program Listing

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Cirrus-logic AN88 Manual de usuario Pagina 12