;
; hello.temp.45.asm
;
; read and send temperature
;
; Neil Gershenfeld
; CBA MIT 10/25/07
;
; (c) Massachusetts Institute of Technology 2007
; Permission granted for experimental and personal use;
; license for commercial sale available from MIT.
;

.include "tn44def.inc"

;
; pins
;
.equ led1=PA2
;
; registers
;
.def bit_count = R16; bit counter
.def temp = R17; temporary storage
.def temp1 = R18; temporary storage
.def compare = R19; data byte
;
;definitions-- the 44 takes in the voltage and compares it to Vcc 
; by the following equation: (Vcc*1024)/Vref-- the accel. defines
; the voltages output by going up or down in the datasheet
;
.equ moving= 512
;
; code segment
;
.cseg
.org 0
rjmp reset

;
; bit delay
; serial bit delay
;
.equ b = 13 ; 9600 baud (clock /8)
;.equ b = 8 ; 115200 baud (clock /1)
bit_delay:
   ldi temp, b
   bitloop:
      dec temp
      brne bitloop
   ret
;

; main program
;
reset:
   ;
   ; set stack pointer to top of RAM
   ;
   ldi temp, high(RAMEND)
   out SPH, temp
   ldi temp, low(RAMEND)
   out SPL, temp
   ;
   ; init LED
   ;
   cbi PORTA, led1
   sbi DDRA, led1
   ;
   ; init A/D--see register description at 
   ; end of ADC Conversion chapter in Datasheet for explanation 
   ; of bit number codes
   ; 
   cbi ADMUX, REFS1 ; use Vcc as reference
   cbi ADMUX, REFS0 ; "
   cbi ADMUX, ADLAR ; right-adjust result
   ;
   ; set MUX to ADC1 (PA1) by settings bits to 000001
   ;
   cbi ADMUX, MUX5 
   cbi ADMUX, MUX4 
   cbi ADMUX, MUX3 
   cbi ADMUX, MUX2 
   cbi ADMUX, MUX1
   sbi ADMUX, MUX0

   sbi ADCSRA, ADEN ; enable A/D
   cbi ADCSRA, ADPS2 ; set prescaler to /2
   cbi ADCSRA, ADPS1 ; "
   cbi ADCSRA, ADPS0 ; "
   ;
   ; start main loop
   ;
   main_loop:

     ;test
	 ;sbi PORTA, led1

	 cbi PORTA, led1
	 
      sbi ADCSRA, ADSC ; start conversion
      AD_loop:
         sbic ADCSRA, ADSC ; loop until complete
	 rjmp AD_loop
	 
	 rcall check

     rjmp main_loop

check: 
	  in compare, ADCL ; low byte
      in compare, ADCH ; hi byte
	  ldi temp, high(moving)
	  cpc temp, compare
      brlo main_loop
      sbi PORTA, led1

	  ret

;1575= up
;2925.7= down