A4988 Unresponsive Board


I wired up my A4988 (minimal wiring) and nothing is happening.

What surprises me: On all 4 Motor Outputs the Voltage reading is exaclty VMOT (20V)

The other readings are:

Reset, Sleep: 4.6V
Enable: 0V
MS1-3: 0V
Step: NC (for testing)

Anyone ever had the same issue?

Thank You


It’s strange that you are measuring a voltage like that on all four outputs. How exactly are you measuring those voltages? Is the stepper motor holding its position (i.e. the stepper motor shaft resists being turned)?

Can you please tell me more about your setup? What stepper motor are you using? What are you using to supply power? What are you commanding the stepper motor driver to do? What do you have the A4988’s current limit set to? Do you have a capacitor across VMOT and GND? Can you also post pictures of your setup that show all of your connections?



thanks for your quick response.

Here are some pictures of my setup:

Im using a pretty standard Nema17 4-lead Stepper Motor, nothing special here. Runs perfectly in other setups.

Originally i told the stepper to do 100 Steps/sec (arduino), also reliable testet on another setup. But for now, i left the DIR and STEP floating. I also set them logic 0 for static testing, nothing changed. I expect holding torque and holding current, but the voltage difference on all 4 motor outputs are zero, and stays here. The pot (current limit) is placed roughly in the middle. Turning it, doesnt alter the output voltage (or current). There is 10uF between VMOT and GND and 1nF on the logic side (5V logic power supply).

It looks like you are using an A4988 carrier board that we do not manufacture. (You can find the A4988 carrier boards we make here.) Since we do not make that board, it is something that we cannot support. You might try contacting the manufacturer of that board directly.