;Expt7.asm
        ;Project: Siren Sound
	;List P = 16F84
	;#include <p16F84.inc>
	;__CONFIG 1Bh    ;_CP_OFF & _PWRTE_ON & _WDT_OFF & _RC_OSC


	ORG 0		;This is the start of memory for the program.
SetUp	BSF 03,5	;Go to Bank 1
	CLRF 06		;Make all port B output		
	BCF 03,5	;Go to Bank 0 - the program memory area.	
	CLRF 06		;Clear display
	GOTO Siren

Siren	MOVLW 80h	;Number of cycles for each tone
	MOVWF 0Eh
	MOVWF 10h
	MOVLW 50h	;Number of steps
	MOVWF 0Fh	;File 0F holds the number of steps
	MOVLW 50h	;Determines frequency
	MOVWF 0Ch	;File 0C determines the frequency
Repeat	MOVF 0Ch,0	;File 0C is moved to W
	MOVWF 0D	;W is moved to file 0D for decrementing
On	BSF 06,7	;Length of HIGH time to Piezo
	DECFSZ 0D,1
	GOTO On		;
	MOVWF 0Dh	;W is moved to file 0D again
Off	BCF 06,7	;Length of LOW time to Piezo
	DECFSZ 0D,1
	GOTO Off	;
	DECFSZ 10h,1	;Number of cycles for each tone
	GOTO Repeat
	DECF 0C,1	;HIGH and LOW is shortened -tone rises
	INCF 0E,1	;Increase the number of cycles
	MOVF 0E,0	;File 0E to W
	MOVWF 10h	;W to file 10h
	DECFSZ 0F,1	;Number of steps
	GOTO Repeat	;
	GOTO Siren

	END		;Tells assembler end of program