LIST P=16F84

__CONFIG 0x3FFB ;RC, NO WDT, PWR-UP, NO CP.

RA EQU 05H ;PORT A

RB EQU 06H ;PORT B

COUNT1 EQU 0CH ;COUNT FOR DELAY LOOP

COUNT2 EQU 0DH ; "

FLAG EQU 0EH ;USER FLAGS

DIT_FLG EQU 00H ;DOT FLAG

DIT_SW EQU 00H ;DOT SWITCH (ON PADDLE KEY)

DAH_SW EQU 01H ;DASH SWITCH (ON PADDLE KEY)

KEY EQU 00H ;KEYING OUTPUT

ORG 00H ;PROGRAM EXECUTION BEGINS FROM HERE

GOTO START

DAH MOVLW 0x1E ;MAIN DOT/DASH DELAY LOOP

GOTO CONT

DIT MOVLW 0x0A

CONT MOVWF COUNT1

LP2 MOVLW 0x6E

MOVWF COUNT2

LP1 DECFSZ COUNT2,1

GOTO LP1

DECFSZ COUNT1,1

GOTO LP2

RETLW 0 ;END OF DELAY

START BSF 3,5 ;SWITCH TO F REGISTER PAGE 1

MOVLW 0FFH ;PORT A ALL INPUTS

MOVWF RA

MOVLW 00H ;PORT B ALL OUTPUTS

MOVWF RB

BCF 3,5 ;SWITCH TO F REGISTER PAGE 0

MOVLW 0

MOVWF RB ;MAKE SURE TX IS NOT KEYED ON POWER UP

MOVWF FLAG ;CLEAR DOT AND DASH FLAGS

NEXT BTFSS RA,DIT_SW ;IS THE DIT PADDLE PRESSED?

GOTO DOT

BTFSS RA,DAH_SW ;IS THE DAH PADDLE PRESSED

GOTO DASH

GOTO NEXT ;LOOP UNTIL NEXT PADDLE PRESS

DOT BTFSS RA,DAH_SW ;ARE BOTH PADDLES PRESSED

GOTO IAMBIC ;YES

DOT2 BSF RB,KEY ;KEY TRANSMITTER

CALL DIT ;DELAY FOR 1 DOT LENGTH

BCF RB,KEY ;UNKEY TRANSMITTER

CALL DIT ;DELAY FOR 1 DOT LENGTH

BSF FLAG,DIT_FLG ;LAST MORSE ELEMENT SENT WAS A DOT (FOR IAMBIC ACTION)

GOTO NEXT ;BACK AND WAIT UNTIL NEXT PADDLE PRESS

DASH BTFSS RA,DIT_SW ;ARE BOTH PADDLES PRESSED

GOTO IAMBIC ;YES

DASH2 BSF RB,KEY ;KEY TRANSMITTER

CALL DAH ;DELAY FOR 1 DASH LENGTH (3 DOT LENGTHS)

BCF RB,KEY ;UNKEY TRANSMITTER

CALL DIT ;DELAY FOR 1 DOT LENGTH

BCF FLAG,DIT_FLG ;LAST MORSE ELEMENT SENT WAS A DASH (FOR IAMBIC ACTION)

GOTO NEXT ;BACK AND WAIT UNTIL NEXT PADDLE PRESS

IAMBIC BTFSC FLAG,DIT_FLG ;CHECK TO SEE IF LAST CHAR SENT WAS A DOT OR A DASH

GOTO DASH2 ;IT WAS A DOT, SEND A DASH

GOTO DOT2 ;IT WAS A DASH, SEND A DOT

END