i have the board A4983 and a Stepper sparkfun.com/datasheets/Robo … 011-25.pdf . The stepper has the wires in the colours yellow, red, blue and green. I want to know which wire comes on which pin?

Thank you for your help.



I don’t have that stepper motor but my experiences says : 6 wires unipolar motors from left to right :

-----    --------
1.        A+
2.        +Voltage (which you wish to feedup)
3.        A-
4.        B+
5.        +Voltage (which you wish to feedup)
6.        B-

for make test, you can use your OhmMeter by measure ;

  1. A+ and A- = should be 10 Ohm (for example)
  2. A+ to +Voltage(pin #2) = should be 5 Ohm (for example)
  3. A+ and B+ or A+ to B- = should be 0 Ohm (zero)
  4. A- and B+ or A- to B- = should be 0 Ohm (zero)

so when that wire defining finishes then you can connect to your A4983 driver board and try to test.
Please let me know results.
sorry for my bad english.

Thanks for your answer. My stepper is a biopolar stepper. It has four wires. The yellow and the blue wires belong togehter and the green and the red wires belong togehter. But i don´t know which wire comes on which pin?

Hi again,

Look attached picture.
There are 2 stepper motors
One is unipolar 6 wire and other one is bipolar stepper

I don’t have your motor so I can’t define wires by their colors.
so we can understand with measuring with Ohmmeter.
from left to right :

  1. Measure to # 1 and # 2 coils. if for example ohmmeter says 10 Ohm
  2. Measure to # 3 and # 4 coils. if for example ohmmeter says 10 Ohm
    if you see these results then #1 is 1A, #2 is 1B and #3 is 2A, #4 is 2B

if it’s not so then try like this

  1. Measure to # 1 and # 3 coils. if for example ohmmeter says 10 Ohm
  2. Measure to # 2 and # 4 coils. if for example ohmmeter says 10 Ohm
    if you see these results then #1 is 1A, #3 is 1B and #2 is 2A, #4 is 2B

These 10 Ohm is sample for you understand simply. Mine is Unipolar and value is 6 Ohm,
your motor can be 8 or 12 or 14. it depends.

I measured the blue and the yellow cable with 3,5 Ohm and the green and the red with 3,5 Ohm. But which cable is #1 or #2 or #3 or #4? I don’t know it.

I guess:

blue to 1A
yellow to 1B
green to 2A
red to 2B

Is it right?

lets define BLUE and YELLOW is coil 1 and GREEN and RED is coil 2
so still we need to test it with driver.
make a connection like so
driver 1A - BLUE
driver 1B - YELLOW
driver 2A - GREEN
driver 2B - RED

it should work with these connections, if it’s not then you change 1A to YELLOW and 1B to BLUE
or 2A to RED and 2B to GREEN. I mean you need to try combinations.


Hello, datatom.

The important thing is that you connect one coil of the motor between 1A and 1B and the other coil between 2A and 2B. The only effect of swapping the coils or reversing the wires on one coil is that the motor might run in the other direction; to fix this, you can just change the wiring or change the state of the DIR pin.

As onurolce said, you should be very careful to remove power from your driver before changing any connections.

- Kevin

You can watch a video in youtube about how to define stepper motor wires

I have a unipolar stepper motor, and am wondering based on the image of the two types of motors for the unipolar stepper where do I connect the A and B leads? Do these connect anywhere to the Pololu driver?

Sorry I pretty much know nothing about steppers, I have a bipolar stepper which I have working but it is extremely small and the only other stepper I have is unipolor and I was hopping to swap it in.


If you have a six-lead unipolar stepper motor like the one shown in the attached image earlier in this thread, you can use it as a bipolar stepper motor by connecting leads A1, A2, B1, and B2 to the A4988 stepper motor driver while leaving leads A and B completely disconnected. If you have a five-lead unipolar stepper motor, then leads A and B are internally connected; it is not possible to use such a stepper motor as a bipolar stepper motor, and it will not work with our A4988 stepper motor drivers.

- Ben