Arm Mbed OS support forum

How to use A4988 corectly?

I am using an A4988 driver to drive a stepper motor (1.3A) recently, but during use, it is found that there is no pulse at the output end, but a high level. I don’t understand it very well.
Details: Use 12V, 3A power supply to power 2 stepper motors at the same time (2 A4988 voltage divider), VDD power supply voltage is an independent 5V voltage source used, only step, VDD, GND, VMOT, GND are connected to A4988 5 ports, VDD and VMOT ground wires are connected together.
I hope someone who has used A4988 will give some suggestions, thank you!

Hello Guo,

You have to use also the DIR input to set the step’s direction prior to making a pulse on the STEP input. For more info have a look at here.