Controller, Driver, Motor - the whole Nine yards

Hello All.

Newbe here!

Just got my first set of hardware in and am very excited.

Here is the list:
1 x #2188 Arduino Micro = 24.95
1 x #352 830-Point Breadboard = 4.95
1 x #312 140-Piece Wire Kit = 5.50
2 x #882 Capacitor: 330uF, 35V, Electrolytic, Radial = 0.98
1 x #1208 Stepper Motor: Bipolar, 200 Steps/Rev, 35×28mm, 10V, 0.5 A/Phase = 12.95
1 x #1182 A4988 Stepper Motor Driver Carrier = 5.95

A few initial observations:

  1. these things are really tiny. I can’t even read the information on the boards with my reading glasses. I have added a magnifying glass to my tools now.

  2. No instruction, data sheet, etc came with anything that I purchased. I do understand they are available online, but I thought maybe they should come with something. In case of the driver, for example, the text online says one of its great features is that the amperage can be controlled by a potentiometer. But the information online doesn’t say anything about which pin, where would you connect one to to it and how it will work.

  3. I know there is a good reason why the motor doesn’t come with mounting screws because every application is probably different. Where should I get the proper screws not knowing their specifications? The motor schematics online only says they are M3 Deep 2.0 Min. I know this probably means a metric 3mm screw but what is the pitch and so on? And the Data Sheet (now that I found it) says the screws are M3 Deep 3.5 Min.

  4. The motor wires are apparently just ready to be permanently soldered on to the driver. Since it will be a while before I am ready to finalize the design, I am going to use four of the headers and solder the wires to them so I can stick them into the breadboard. Clever, hah?

  5. I have an old AC to DC power supply that satisfies the voltage and amperage requirements of the system. I need to get the plug for it and I guess I need to make a trip to the local Radio Shack.

  6. I winded up getting the 300 uf capacitor because Pololu didn’t have the 100 uf ones. I am not sure if the 100 uf would have been any more compact, but the 300 uf one is huge in comparison. Something else on my list at Radio Shack.

And what are Eagle Files? I am using a Mac and when I download it I am not able to see what they are and what they are good for.

Does anyone know if the Arduino Micro uses Micro A or B plug? I was on the Arduino site and can’t find that information. It could be that either would work.

I appreciate any feedback. My project is a barn door star tracker mount and it is very simple to put together. I don’t need a degree in electronics, in other words to do that. But these are fascinating toys with all their capabilities.


Hi, Farzad.

You do not need to add an external potentiometer. You can set the current limit of our A4988 carrier by adjusting the potentiometer on the board, which is shown at the bottom of this picture:

The mounting holes on that stepper motor should work with an M3x0.5 screw. In general, if no pitch is specified for a screw like that, it is assumed that the standard pitch is used. The minimum depth should be 3.5mm. Thank you for pointing out the inconsistency between the diagram on that motor’s page and the one in its datasheet; we are looking into it.

Eagle files are files for a CAD software called Eagle. They usually contain schematics or PCB layouts. A free version of the software can be downloaded from the CadSoft website.

The Arduino Micro uses a USB Micro B connector.


Thanks, Claire. Any idea where I can get those mounting screws from? Strange that the motors don’t come with any.


A barn door star tracker is an great project! If you are following some instructions on line, others would probably appreciate a link.

Most well stocked hardware outlets have M3 screws (this is an international metric standard, which authorities in the backward country between Mexico and Canada refuse to adopt). The length will need to be compatible with the thickness of the panel to which you are mounting the motor.


I have found the screws on Polulo also. I have them in my cart.

I’d be happy to share the links although a Google search is all that is needed. Where do you suggest I post the links? What forum?



Your original post is a good place for informational material.