When the stepper motor driver is in a certain phase with its power turned off, and if the phase is different from the phase at the time of next power-on, the motor will "jitter". In order to eliminate the jitter, the phase at the time of power-off must be remembered. There are 8 steps when the stepping motor runs. If you stop at step 4 and re-power it, if you start driving step 1 directly at position 4, a jump will occur. If the system can still remember that it is still in step 4, then you can correctly issue the command to go to step 5 or step 3.

         A stepper motor driver is an actuator that converts electrical pulses into angular displacement. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (called the "step angle") in a set direction, and its rotation is performed step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses to achieve the purpose of accurate positioning. At the same time, the speed and acceleration of the motor rotation can be controlled by controlling the pulse frequency, thereby achieving the purpose of speed regulation and positioning.

         In fact, most stepper motor drivers do not have a power-down phase memory function, especially a stepper driver using a common dedicated IC. The reset signal of the reset pin after the dedicated IC is powered up will reset the motor phase to the initial value, and the power-on jitter should be unavoidable. Even if it is a servo motor with an absolute value, it has to be judged and corrected, and can also be regarded as jitter. Or strictly speaking, there is no motor that does not shake on power. The key is how much impact this jitter has on your application. It is best to record the absolute stop coordinates. After power-on, the system resets the checkpoint and then runs to the absolute coordinate recovery operation before power-off.