Hi folks, Just got my first order of electronics from Pololu. I had a question on the motor wiring to the driver. Have the little 200 step per rev 3.8V .67 A/phase and one coil pair is black/green the other red/blue. It has been a long time since I have worked on electronics project but if I remember right a coil does not care about polarity, correct?
In other words will it matter what wires are connected as long as one coil set from the motor is connected to the 1 A/B set on the driver?
edit: just a little later that same day After more research I found that I had miss understood the wiring info and how it connected the motor to the driver. Thankfully I did not power anything up.
I love how all the info to do things right is all there, just disjointed enough that a new person can mess things up!. With that being said I found https://forum.pololu.com/t/a4983-and-a4988-getting-started-guide/2789/1decrDude’s summery very helpful and have it downloaded. I think his summery is worth a ‘sticky’ so it stays at the top of this forum.
I know that the A4988 driver is no doubt used on countless brands of steppers but if i could suggest, it would be nice to reference very clear hook up directions for some of the motors offered by pololu. For me it took noticing one image on the motor listing that showed the colors that correlated to the letters, then reading the text below to find what letter connected to what pin out on the driver.
The polarity of the coil pairs would affect the direction of the stepper motors rotation. As long as one of the coils is connected to the 1 A & B pins and the other to the 2 A & B pins, you should be fine. You can change the direction of the stepper motor’s rotation by either reversing the polarity of one of the coils, or inverting the signal to the DIR pin. Please note that disconnecting a stepper motor while it is powered could damage the stepper motor or driver. The “Minimal wiring diagram for connecting a microcontroller to an A4988 stepper motor driver carrier (full-step mode)” on the A4988 carrier’s product page should be helpful in connecting your A4988.
Derrill,
You know I passed right by the first driver, opting for the one with pre soldered headers. looked right past the link to read the additional info you just listed. Helpful to know about needing the 47uF cap. It said at a minimum. What would be max? Would this do the job? https://www.pololu.com/category/18/passives as I’m likely doing another parts order with Pololu.
Thanks for the reply. Part of what spurred the question was a web page showing a single power supply for his stepper driver and the arduino. He had 4 sizes of capacitors shown ( did not bookmark the page and I have not found it again to link to ) claiming each one filtered out AC noise of different frequencies. Some thing like 47uF down to .0001uF.
My thought was to buy this https://www.pololu.com/product/1468 rather than looking for the cheapest. I’m only running one motor at .670 amps per coil. Should one still expect to use a capacitor to reduce noise from a regulated unit?
Yes. The capacitor is not there to reduce noise, but to reduce potentially damaging LC voltage spikes as explained on the product page for the motor driver.
Hi Jim,
I used the term noise referring to voltage spikes. I’ve seen spikes called noise in other readings but to be clear, I’m wanting to be as sure as possible that voltage spikes from the power supply ( regulated or otherwise ) will not trigger other problems with the Arduino. So even from a regulated supply one can get voltage spikes.
I’ve been attempting to find the fritzing.org page that showed a single power supply feeding the Arduino and the driver board. There was 4 capacitors on it. 2 electrolitic and 2 ceramic. The sizing had to do with each capacitors ability to stop voltage spikes of differing frequencies.
Anyhow it would be great to find that page and read it over again. Maybe the typical spikes that cause troubles for the Arduino are pretty well handled by at the min a 47uF and all the others are just " fluff " that give guys like me some thing to wonder about.
