need help for at89c51 project

this is my first project ever regarding microcontrollers..
i am making rpm counter from at89c51 microcontroller..i have done all coding in assembly language.. implemented in protious ..the rpm will be shown as bar graph display conted to 3 ports... now the problem is that am using timer 1 as counter..in protious i provided it with pulse of 5 volts and it works great..but the pulse from ignition coil is about 22v peak and is sharp..i tried my best to clip it and remove the lower pulse..i made it close to digital best i could(p.s i used sine wave in protious as i couldn't reproduce pulse signal that of ignition in protious).. but it didnt work..also the rise time isnt that much. so i have uploaded some screenshots..where i have made a clipper circuit and the other screenshot which compares the pulse wave(blue) and clipped wave(yellow).not much difference..
am i doing it right?
is there any other way of doing it.
is there something wrong with my protious?
i really need help..as am running out of time..:bang:

these are screenshots..

you can use Schmitt Trigger for better result

i had no idea what it was.. but googled it..so now i can finally complete my project.. thankyou for reply..