-About the operational amplifier, on the first configuration it was not working as an amplifier as ERIC said. i search about that with my team and we figured out that, it is working as an insulator buffer
between the input voltage coming from the RV1 and the output voltage of the opamp to the pin9(Verf/2).
The reason is to guarantee that the value RV1 is stable it will not make Vref stable because sometimes, even the pin9 is an input pin and logically, it must not carry any value on it ( no voltage ) its Vref ,
but practically , if u measure the value of it, you will notice that carries some voltage, so this value will included to that coming from RV1which mean, the results will be an expected . Sorry, this part dosnt make any sense
WHAT DO YOU THINK GUYS ? CORRECT ME IF I've MISTAKEN
-Finally, i want to talk about the Vref I applied , as follows :
Vref=1.28 v then we will apply Vref/2=0.64 v on the pin 9 .
according to the formula [LM35/Vref]*255
WHAT WILL BE THE TEMPERATURE ? as eric calculated on 2.5 v