;*************************************************************
;*
;* Title        : 8535_ADC.ASM Test
;* Version      : 1.0.1
;* Last updated : 1999-06-18
;* Target       : AT90S8535
;*
;* Author       : Lars Wictorsson / LAWICEL
;*                http://www.lawicel.com
;*                info@lawicel.com
;*
;* Info         : Program reads ADC channel 0 all the time
;*                (as fast as possible), then convert the
;*                10bit data to 8bit data and display the
;*                value on port B.
;*
;* Revision     : 1.0.0 Created 1999-02-15
;*                1.0.1 Optimizing conversion fom 10 to 8 bits
;*
;*************************************************************

.include "8535def.inc"

.def	TEMP	=R16
.def	TEMP2	=R17

.CSEG

	rjmp	MAIN		; Reset Handle
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	reti
	rjmp	ADCRDY		; ADC Conversion complete
	reti
	reti

;*
;* Interrupt routine for ADC
;*
ADCRDY:
	in	TEMP,ADCL	; Read 10 bit ADC value
	in	TEMP2,ADCH
        ror     TEMP2           ; Divide ADC value by 4
        ror     TEMP
        ror     TEMP2
        ror     TEMP
	sbi	ADCSR,6		; Trigger next conversation
	reti
;*
;* Main program
;*
;* Start here after a RESET.
;*
MAIN:
	ldi	TEMP,$57	;Initialize stack pointer at $0257 (Max RAM)
	out	SPL,TEMP	;Stack pointer decreases when something is
	ldi	TEMP,$02	;pushed on the stack.
	out	SPH,TEMP

	ldi	TEMP,0xff	;Set PB port to output
	out	DDRB,TEMP
	ldi	TEMP,0x00	;Set all PB pins to OFF
	out	PORTB,TEMP

	ldi	TEMP,$00	;Set ADMUX channel 0
	out	ADMUX,TEMP
	ldi	TEMP,0b10001000	;Set ADC enable and trigger dummy read
	out	ADCSR,TEMP
	sei			;Set Global interrupt flag
	sbi	ADCSR,6		;Trigger next conversation


LOOP:
	rjmp	LOOP



;*
;* End of program
;*