doubt regarding 89c51 i/p

I am getting a sine wave from an band pass filter and using a schmit trggr ckt, i am shaping it as a square wave, i want it to feed to MCU. I am using 89c51 for operating a 12v relay( by generating PWM).
Now the problem is that i have to level shift the schmit trigger o/p (1.22v- 1.88v) to a digital pulse (h1gh or l0w) so as to use it to MCU i/p.
how can i do this?
can u plz help me?



Vth+ | |----| |----|1.88v
vth- |__| |__| |1.22v

_________0v
.
.
.
o/p reqd: .

__________________1
|_________0

_

use diode clamping circuit.. for level shifting. google it for more information of clamping circuits..