You are not supposed to GET any waveform from the motor.
You are supposed to SEND it to the motor. There are couple of
patterns that you have to repeat in one or another direction
depending on desired motor direction. Valid patters range from
simple "walking 1's" till more sophisticated microsteping.
Patters are usually stored in a lookup table and read sequencially
depending on direction. Make sure to disable invalid output states
so you don't fry your H-bridge. Try to do some research on motor
wiring as well.