I have a PIC16F84A chip with 4mhz crystal and want to store four =
frequencies ex: 1khz , 1.2khz , 1.5khz , 2khz  then  I need the chip to =
work like a high speed switch so I can send those four frequencies out =
into our modulator it must switch at least 10 or higher times a second =
and it must loop continiously and send each frequency out to one port =
pin only such as portb1.

Thank You
Keith


                               LIST P=3D16F84A
                               #INCLUDE<P16F84A.INC>
              _CONFIG_CP_OFF_WDT_XT_OSC_PWRTE_ON


org           0

CLRF      PORTB                 ;CLEAR PORTB OUTPUT
BSF        STATUS,RP0        ;SELECT REGISTER BANK 1
BCF        TRISB,1                ;SET RB1 AS OUTPUT
BCF        STATUS,RP0        ;GO BACK TO BANK 0

FREQ1     EQU        d'1000'        ;output freq in hertz
CLOCK     EQU       d'4000000'    ;clock freq in hertz
#DEFINE  PIN         PORTB,1     ;output pin

;VARIABLES
CBLOCK                h' 0c'
COUNTER
ENDC

delay     equ      clock/(2*FREQ*d'16')  ;delay clock
loop       bsf       pin                           ;pin high [4]

;-1 to account for overhead in setting up the loop
movlw       delay   -1   ;[4]
movwf       counter      ;[4]
nop                           ;[4]

;inner loop always takes 16 cycles
loop         clrwdt           ;[4]
decfsz     counter         ;[4/8]
goto        loop              ;[8/0]
nop                             ;[0/4]

;depending on the choice of clock and frequency you might need some =
extra nop;s in here(if delay is non integral
;nop               ; [4]
bcf     pin        ;pin low [4]

;-1 to account for overhead in setting up the loop
movlw          delay     -1        ;[4]
movwf          counter             ;[4]
nop                                     ;[4]

;inner loop always takes 16 cycles
loop       clrwdt          ;[4]
decfsz   counter        ;[4/8]
goto      loop             ;[8/0]
nop                          ;[0/4]

;depending on the choice of clock and freq you might need some
;extra nop's in here(if delay is non-intregral)
;nop    ;[4]
goto       loop
end
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