; Garage Door Minder
; Atmel AVR Assembly
; William Riley  riley@randdtechnologies.com
; http://workbench.freetcp.com/

.NOLIST
.INCLUDE "tn12def.inc"
.LIST

.def	T1	= r1
.def	T2	= r2
.def	temp	= r16
.def	btime	= r17

.ORG $0000
	rjmp	reset
	reti				;external interrupt handler

;with 1MHz clock should give ~200ms delay
longDelay:
	clr	T1
	clr	T2
delay_1:
	dec	T2
	brne	delay_1
	dec	T1
	brne	delay_1
	dec	temp
	brne	delay_1
	ret


reset:
	.equ	led = 0		;LED at PB0
	.equ	radio = 1	;radio signal at PB1
	.equ	X = 3		;blink on/off every X*200ms 

	sbi	DDRB,led	;PB0 set to output 
	cbi	DDRB,radio	;PB1 set to input

	cbi	PORTB,led	;LED on
	ldi	temp,1
	rcall	longDelay
	sbi	PORTB,led	;LED off
	ldi	temp,1
	rcall	longDelay
	cbi	PORTB,led	;LED on
	ldi	temp,1
	rcall	longDelay
	sbi	PORTB,led	;LED off
	ldi	temp,1
	rcall	longDelay
	cbi	PORTB,led	;LED on
	ldi	temp,1
	rcall	longDelay
	sbi	PORTB,led	;LED off

main:
				;Go to sleep.
	ldi	temp,$30	;enable sleep and set T0 to respond to low level
	out	MCUCR,temp	;enable sleep mode
	ldi	temp,$40	;enable external interrupt 0	
	out	GIMSK,temp   
	sei			;assure interrupts are enabled
   	sleep			;good night. Wait for radio to go low (interrupt 0)

blink:
	ldi	btime,5		; blink on/off 5 times ~3 seconds
blink2:
	cbi	PORTB,led	;LED on
	ldi	temp,X
	rcall	longDelay
	sbi	PORTB,led	;LED off
	ldi	temp,X
	rcall	longDelay
	dec	btime
	brne	blink2
	rjmp	main