Reading from a pin Arduino Uno (assembly) I am creating a project in which an Arduino reads (gets) a value from
a DHT sensor. The DHT sensor returns two values:


Temperature
Humidity 




My assembly code:

sbi ddrd,5
cbi ddrd,2
sbi portd,5

start:

in r16,Pind2
cpi r16,80
brne On

jmp start

On:
cbi portd ,5
jmp start


After the code, the light remains turned on, but if the sensor sends '80' 
and I get it correctly it should be turned off.

Question: Am I Using the write way to read a pin?
You are simply reading the state of the input pin - this won't work.

Study the datasheet for the DHT22, available from Sparkfun or eslewhere.

To get data from the DTH22, you must first send a start signal, wait a specified time, then watch the level of the data line, measuring the time of each bit to determine whether it is a 1 or 0, and store the bits in five 8-bit variables.  You can then examine those variables to determine the temperature and humidity.