SLOSE70 December 2020 DRV8434S
The first step in configuring the DRV8434S requires the desired motor speed and microstepping level. If the target application requires a constant speed, then a square wave with frequency ƒstep must be applied to the STEP pin. If the target motor speed is too high, the motor does not spin. Make sure that the motor can support the target speed. Use Equation 2 to calculate ƒstep for a desired motor speed (v), microstepping level (nm), and motor full step angle (θstep)
The value of θstep can be found in the stepper motor data sheet, or written on the motor. For example, the motor in this application is required to rotate at 1.8°/step for a target of 18.75 rpm at 1/8 microstep mode. Using Equation 2, ƒstep can be calculated as 500 Hz.
The microstepping level is set by the MICROSTEP_MODE bits. Higher microstepping results in a smoother motor motion and less audible noise, but requires a higher ƒstep to achieve the same motor speed.