Stepper motor through direct current, motor shaft has the feeling of locking, which is reasonable. If the pulse current is passed in accordance with the correct timing, the motor does not turn, then the reason is determined according to the phenomenon of not turning.
The reason for not turning excludes the circuit connection error, poor contact, program error and other reasons, the most likely is: the pulse frequency is too high. The stepper motor starts at a lower frequency and then slowly accelerates to a higher frequency.
The current of the motor is too small and the load is too large, the general stepper motor driver chip has to set the current size, or control the PWM duty ratio from the PWM output end of the control chip to increase the current.
The output port drive capability of the control chip is insufficient, and the stepper motor drive chip cannot detect the input. Especially in the case of optocoupler isolation, the pull-up resistor should be used to increase the output capacity of the port.