H bridge UPD16837

Hi

Well i have got it to go back and forth now but just by using high and low pins (pin 9 = select, pin 10 = in1, pin 11 = in2) and using a logic shifter from 5V to 3.3V. however, i want to use a pwm to control the speed

First usually i would have the pwm go through the select pin is that still the case? if not would i need to send pwm directly to pin 10 and 11.

Secondly i believe the reason the pwm sginal might not be working could be because i dont think im generating a 120khz pwm, to be honest i have not done something like this before where i need to get a pwm at 120khz it is why i thought to use the library Timezone , so any help with that would be great

Thank you