Hello there,
i have looked for a similar thread but i didnt find any.

I use a DS89C450 and a Humidity and Temperature sensor to measure temperature and humidity. They communicate using I2C protocol. I wrote the code using assembly language (i dont know C)
The results i get are wrong.
I probably have a problem using I2C protocol.
This is a part of code i've written so someone tell me whats the problem.



sda equ P3.0 ;data pin
scl equ P3.1 ;clock pin
en equ p2.5 ;lcd comunication enable pin
rs equ p2.3 ;lcd data/command pin
r_w equ p2.2 ;lcd read/write pin


;__________________________________TEMPERATURE___________________________________



clr c
mov a,#00000011b ;00000011 <-- Measure temperature command
mov r3,#08d
temp: ;Sending the temperature command
rlc a
mov sda,c
setb scl
acall delay1
clr scl
acall delay1
djnz r3, temp

jnb sda,$


mov r4,#03d
mov r0,#50h ;1st temperature byte saved at memory


t1: mov r3,#08d
clr c
clr a

t2: ;Receive Temperature measurement bit-by-bit
mov c, sda
rlc a
clr scl
acall delay1
setb scl
acall delay1
djnz r3,t2 ;do it for 8 times

mov @r0,a ;store byte
inc r0

clr sda ;send ack
clr scl
acall delay1
setb scl
acall delay1

djnz r4,t1


acall print_Temp
acall delay



;___________________________DISPLAY TEMPERATURE_________________________

print_Temp:
setb en
clr r_w
clr rs
mov p0,#80h ;move to 1st line
call lcd_delay

setb rs
mov p0,#'T' ;print "T"
acall lcd_delay
mov p0,#'e' ;print "e"
acall lcd_delay
mov p0,#'m' ;print "m"
acall lcd_delay
mov p0,#'p' ;print "p"
acall lcd_delay
mov p0,#'=' ;print "="
acall lcd_delay

mov r4,#03d
mov r0,#50d
ptemp1:
mov p0,@r0 ;print data
acall lcd_delay
inc r0
djnz r4,ptemp1


clr rs
ret