Need help finish temperature sensor using asm code

hi wondering if anyone can help me out with this, ive got the lcd displaying information, but i want it to display the temperature using the lm35 and adc0804 as well, using asm code. Basically i need to get the current reading from the lm35 and convert them in the adc0804 and then display that reading in degrees on the lcd display. I have found some similar projects like this but they were written in C. any help needed, thanks in advance

current embedded image
http://www.flickr.com/photos/6024224...in/photostream

current code:

Code:

---

$mod51
rw equ P3.1
rs equ P3.0
en equ P3.2

org 0000h

clr rw
acall lcd_init
main:
mov a, #'W'
acall lcd_data
mov a,#'e'
acall lcd_data
mov a, #'l'
acall lcd_data
mov a,#'c'
acall lcd_data
mov a, #'o'
acall lcd_data
mov a,#'m'
acall lcd_data
mov a, #'e'
acall lcd_data
mov a,#' '
acall lcd_data
mov a,#'K'
acall lcd_data
mov a,#'e'
acall lcd_data
mov a,#'i'
acall lcd_data
mov a,#'t'
acall lcd_data
mov a,#'h'
acall lcd_data
sjmp $


lcd_init:
mov a,#01h
acall lcd_cmd
mov a,#38h
acall lcd_cmd
mov a,#0ch
acall lcd_cmd
mov a,#06h
acall lcd_cmd
ret


lcd_cmd:
clr rs
mov p2,a
setb en
acall delay
clr en
ret

lcd_data:
setb rs
mov p2,a
setb en
acall delay
clr en
ret

delay:
mov r0,#5h
l2: mov r1,#0ffh
l1: djnz r1,l1
    djnz r0,l2
ret



end

---

[HTML]

What processor / microcontroller are you using?
Do you know the code for reading from the ADC?
What range of numbers does the ADC give and how do they correspond to the temperature?
Is the temperature to be displayed in Celsius or Fahrenheit?

its an 8051 micro controller. at89c51
i think it will be something along the lines of this, correct me if im wrong

Quote:

---

rd equ P1.0 ;Read signal P1.0
wr equ P1.1 ;Write signal P1.1
cs equ P1.2 ;Chip Select P1.2
intr equ P1.3 ;INTR signal P1.3

adc_port equ P2 ;ADC data pins P2
adc_val equ 30H ;ADC read value stored here

org 0H
start: ;Start of Program
acall conv ;Start ADC conversion
acall read ;Read converted value
mov P3,adc_val ;Move the value to Port 3
sjmp start ;Do it again

conv: ;Start of Conversion
clr cs ;Make CS low
clr wr ;Make WR Low
nop
setb wr ;Make WR High
setb cs ;Make CS high
wait:
jb intr,wait ;Wait for INTR signal
ret ;Conversion done

read: ;Read ADC value
clr cs ;Make CS Low
clr rd ;Make RD Low
mov a,adc_port ;Read the converted value
mov adc_val,a ;Store it in local variable
setb rd ;Make RD High
setb cs ;Make CS High
ret ;Reading done

---

the temperature will range from using the voltage formula
so 1v=100 degrees Celsius
.50v= 50 degrees Celcius

it is to be displayed in Celcius

One you have a numeric representation of the temperature stored in adc_val, you just need to convert that number (I am guessing it is between 0 and 255) to degrees Celsius and then display that Celsius number as characters on the LCD.

I am not familiar with the 8051 microcontroller so I do not know what instructions are available, specifically if it can multiply or divide. Being able to divide by ten would be helpful. It might be easier to first determine how many characters are needed to display the temperature by comparing it with 10 or 100. One piece of code could handle temperatures between 0 and 9, another piece of code could handle temperature between 10 and 99, and another could handle temperatures 100 and more. You could even do a series of comparisons or subtractions to further break the temperature into groups of 10 to 19, 20 to 29, 30 to 39, ... The goal would be to get each digit of the temperature to be a value between 0 an 9. That number would then be converted to the character code for '0' to '9' by adding the value for character '0'.

Another approach, if ample memory is available, is to create a table of character strings, with one character string for each value of adc_val. For example, if each temperature would displayed as four characters, such that temperatures below 100 would have a decimal point and a tenth of degree, then you would need 4 x 256 = 1024 bytes to store the table. Your code would then simply convert the adc_val value to a table index by multiplying by the character string length. To multiply by four, you could shift the value to the left by two bits or add the value to itself a couple times.

I hope this gives you some ideas.