;	AVR software UART demo by Randy Ott - 4/22/98
;	Read contents of EEPROM and put result on port B

;***** Global register variables

.def	temp	=R16		;temporary storage register
.def	EEard	=R17		;EEPROM address pointer
.def	lights	=R18		;LED holding register

.cseg
.org 0
	rjmp	reset

;***** Program Execution Starts Here
.org 16				;avoid all possible interrupt vectors

reset:
	ldi	temp,0xff	;port B pins all outputs
	out	DDRB,temp
	ldi	lights,0	;turn on all LEDs
loop:
	ldi	EEard,0		;set EEPROM address to 0
EERead:
	sbic	EECR,EEWE	;if EEWE not clear
	rjmp	EERead		;    wait more
	out	EEAR,EEard	;output address
	sbi	EECR,EERE	;set EEPROM Read strobe
				;This instruction takes 4 clock cycles since
				;it halts the CPU for two clock cycles
;	sbi	EECR,EERE	;set EEPROM Read strobe 2nd time
				;This instruction takes 4 clock cycles since
				;it halts the CPU for two clock cycles
	in	temp,EEDR	;get data from EEPROM
	com	temp		;invert data
	or	lights,temp	;set bits
	out	PORTB,lights	;show it on LEDs
	inc	EEard		;point to next EE address
	cpi	EEard,63	;see if at end of EEPROM
	breq	loop		;    if so, start over
	rjmp	EERead

.eseg
.org 0
	.db	0x55

.include "1200def.inc"