The Driver provides five different step resolutions: full-step, haft-step, quarter-step, eight-step and sixteenth-step. Also, it has a potentiometer for adjusting the current output, over-temperature thermal shutdown and crossover-current protection.

1. A4988 Stepper
2. Pololu Stepper Driver Board

Its logic voltage is from 3 to 5.5 V and the maximum current per phase is 2A if good addition cooling is provided or 1A continuous current per phase without heat sink or cooling. A4988 Stepper Driver Pinout Now let’s close look at the pinout of the driver and hook it up with the stepper motor and the controller. So we will start with the 2 pins on the button right side for powering the driver, the VDD and Ground pins that we need to connect them to a power supply of 3 to 5.5 V and in our case that will be our controller, the Arduino Board which will provide 5 V.

The following 4 pins are for connecting the motor. The 1A and 1B pins will be connected to one coil of the motor and the 2A and 2B pins to the other coil of the motor. For powering the motor we use the next 2 pins, Ground and VMOT that we need to connect them to Power Supply from 8 to 35 V and also we need to use decoupling capacitor with at least 47 µF for protecting the driver board from voltage spikes. The next two 2 pins, Step and Direction are the pins that we actually use for controlling the motor movements. The Direction pin controls the rotation direction of the motor and we need to connect it to one of the digital pins on our microcontroller, or in our case I will connect it to the pin number 4 of my Arduino Board.

With the Step pin we control the mirosteps of the motor and with each pulse sent to this pin the motor moves one step. So that means that we don’t need any complex programming, phase sequence tables, frequency control lines and so on, because the built-in translator of the A4988 Driver takes care of everything. Here we also need to mention that these 2 pins are not pulled to any voltage internally, so we should not leave them floating in our program.

Next is the SLEEP Pin and a logic low puts the board in sleep mode for minimizing power consumption when the motor is not in use. Next, the RESET pin sets the translator to a predefined Home state. This Home state or Home Microstep Position can be seen from these Figures from the A4988 Datasheet. So these are the initial positions from where the motor starts and they are different depending on the microstep resolution. If the input state to this pin is a logic low all the STEP inputs will be ignored. The Reset pin is a floating pin so if we don’t have intention of controlling it with in our program we need to connect it to the SLEEP pin in order to bring it high and enable the board. The next 3 pins (MS1, MS2 and MS3) are for selecting one of the five step resolutions according to the above truth table.

These pins have internal pull-down resistors so if we leave them disconnected, the board will operate in full step mode. The last one, the ENABLE pin is used for turning on or off the FET outputs. So a logic high will keep the outputs disabled. Components needed for this Arduino Tutorial You can get the components from any of the sites below:. Stepper Motor (NEMA17). /.

A4988 Stepper Driver. /.

12V 2A Adapter. /. Power Jack /. Arduino Board /.

Breadboard and Jump Wires. /.Please note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

Circuit Schematics Here’s the complete circuit schematics. I will use the drive in Full Step Mode so I will leave the 3 MS pins disconnected and just connect the Direction and the Step pins of the drive to the pins number 3 and 4 on the Arduino Board and as well the Ground and the 5 V pins for powering the board. Also I will use a 100µF capacitor for decoupling and 12V, 1.5A adapter for powering the motor. I will use a NEMA 17 bipolar Stepper Motor and its wires A and C will be connected to the pins 1A and 1B and the B and D wires to the 2A and 2B pins. Current Limiting Before we connect the motor we should adjust the current limiting of the driver so that we are sure that the current is within the current limits of the motor. We can do that by adjusting the reference voltage using the potentiometer on the board and considering this equation: Current Limit = VRef x 2 However this equation is not always correct as there are different manufactures of the A4988 driver board.

Here’s a demonstration of my case: I adjusted the potentiometer and measured 0.6V reference voltage. So the current limiting should be that value of 0.6.2, equal 1.2 A. Now because I am using the Driver in Full Step Mode and according to the A4988 Datasheet in this mode the winding current could reach only 70% of the current limit, the 1.2A.0.7 would equal 0.84A. In order to check this I uploaded a simple code that sends continuous logic high to the Step pin (so that we can better notice the current) and connected my meter in series with one winding of the motor and powered it up. What I got was 0.5A which means that the equation wasn’t correct for my case.

A4988 Stepper

Ralph Brown Hi’ Thanks for this tutorial. I’ve been trying for weeks to run 3 steppers on a Uno with a motor shield and A4988’s.

I’ve had no success at all and thinking I had fried everything, bought full replacements, with the same results. Thanks to your tutorial I’ve at last managed to get a positive result.

I’ve also now been able to test all the A4988s, my 2 Uno boards and the steppers. Interestingly, I didn’t fry anything! I’ll now need to think about how to test the shields.

Thanks again, Ralph. Argyris Hello I’m trying to control a stepper motor with a joystick, a DRV8825 and an arduino uno. I used your tutorial with the potentiometer, but I have some difficulties with the speed. In your tutorial you have only one direction and your values are from 0 to 1023.

I want to devide the potentiometer for RIGHT and LEFT direction, any suggestions on how to do that? Also, the speed on my motor is slower than your tutorial(When the motor turns clockwise and anticlockwise). Thanks in advance, still your tutorial was very helpfull. Nick Great tutorial! I got everything to work with the potentiometer after playing around with it for a bit.

Pololu Stepper Driver Board

Now I want to add another motor/potentiometer to the same Arduino board. I tried copying everything you had in potentiometer code and just renamed and add a few variables. I was successfully flashed my code to my Arduino Uno but when I changed one potentiometer both motor speeds would change at the same time.

I can’t figure out how to get each motor to work independently. Any suggestions?

Steve OBrien, Sydney, Australia Thanks for this tutorial, I have used your information to successfully get my A4988 board & stepper motor project working. It saved me a lot of time! But I did have to change the stepper wiring, the illustration shows the wires straight through from the motor into the A4988 board, but I had to cross them over. My stepper is a NEMA 17HS3001-20B it has 4 wires and similar looking connections on the motor. Would it be worth adding a warning about this in the next version of your page? Respected sir, I have seen your video on How to control a stepper motor it is a good and nice tutorial.

Sir I have question, sir I want to control a stepper motor’s rotation angle from 0 to 360 and 360 to 0,with a potentiometer. Sir there is an example skech in the Arduino software, called stepper motorknob. Sir in that example skech four control inputs are there, by using A4988 driver board that skech is not going to run the motor. Sir please throw some light on this.

Or can u suggest some skech on this without using library thanking you Manas. Maddie Hi Dejan, Thank you for this great tutorial.

I have two questions: in the video, the circuitry diagram (the one that looked like a Fritzing image) does not show that the Sleep and Step pins are connected. Yet it appears as if they are at the end of the video?

Could you clarify for me which is the correct circuit? And secondly, more importantly, I am finding that my stepper motor, an FSM0815-KD95, is getting extremely hot. After checking the voltage of the 1A-2B driver pins, I found that even when my code was simply looping “digitalWrite(stepPin, LOW);” two of the pins are still receiving voltage. Is there anyway that I can make the voltage of all pins 0 while the motor is not running? That way it will not overheat.