single-chip stepper motor control, subdivision 2, a step of 0.9 degrees, walk around 400 pulses required radius 33mm, around 20 laps to go away need 0.10362m 8000 pulses. Accelerated to 4000, the slowdown of 4000, when Timer 0 period of 60ms to 40ms when the period of 7.8s 5.2s