[tech_vaibhav_ee]

thanks for your replies!!!
@mahul..you seems to be wrong on just one point here(i asked this question on other forums also, so i am very much clear of the answer... .)

its true that a microcontroller gives digital 1 or 0 for certain input voltages but these these limits are defined by the hardware itself and not by the user...generally a microcontroller gives a digital 0 for 0v-1v and digital 1 for 3v-5v(these are approximate values which changes from hardware to hardware)...if the input voltage is outside these limits then it may even damage the microcontroller...