I want to hook this up either in series or parallel. From what I have read parallel will give me more power and speed but will generate more heat. I am using a power supply from a computer to power this so I can use 3.3, 5 or 12V. I actually have it so I can get 24V by using 2 of the power supplies that I have hooked together.
However I also read in the FAQ about the stepper driver that I should wire it in series. Either will be fine for me I think. What is confusing me is on my stepper driver there is 1B 1A 2A and 2B and I am not sure where I should be hooking it up.
I was hoping someone could give me some advice or what to hook to what to make this work.
The FAQ contains a labeled stepper motor diagram like the one in your datasheet and tells you what wires to connect to which pins of the stepper motor driver (it makes specific mention of driver pins 1A, 1B, 2A, and 2B). Note that in the FAQ, the paired coils are AC and BD while in your diagram, the paired coils appear to be AB and CD, so if you mentally swap B and C while reading the FAQ, you should be set. I’m happy to confirm your connections are correct if you want to run them by me before actually making them.
If you have not already done this, you should be very careful and make sure you know what you are doing before trying to connect two power supplies in series. If the grounds on the power supply outputs are connected to the AC mains ground, you could create a short if you try to “stack” the voltages by connecting ground on one supply to the 12 V line on the other.
Thanks Ben I just dont know anything about this stuff. Heck I didnt know what a stepper motor was till earlier this week.
Now that I got it working I think lol! I am going to try hooking up 3 different motors using 3 driver boards and then I am going to try and get Mach 3 or some sort of program to send code to it.
So far things seem to be going pretty good. I am pretty sure I got it wired right and am able to control the stepper like I want. The concerns I have are the torque at higher speeds I am getting. I was doing some reading and found that in series I will get lower torque at higher rpms. I am pretty sure that is how I have it set up now. I also read that its recommended to wire the motor in series with the a4988. So my question is can I wire it in parallel and if I do will I gain more torque at higher rpm with the A4988 stepper driver? If I can what will my wiring look like?
Also I would like to find out how much current the motor is using so I can set the potentiometer correctly for maximum efficiency. I tried this by hooking my multimeter to the ref pin and to the Gnd pin. When I did that it reset my PSU and then 2nd time it burnt my chip up. I may have had things wired up wrong when I did this though so that may have been my problem. The thing is I am apprehensive on doing it again so I would like to know what the correct way is.
While a parallel configuration can generally provide a performance boost, it requires twice the current to do so, and I do not think the A4988 motor driver carrier can deliver the current required to make this option worthwhile for your particular motor. Your stepper motor can handle 0.96 A per phase, which is pretty close to what the A4988 driver carrier can deliver without overheating (assuming you haven’t added a heat sink or taken additional steps to keep the driver cool). To get a performance boost from a parallel configuration, you would need to provide ~2 A per phase, and I don’t think you will be able to keep the A4988 cool enough to run while delivering that much current.
Since it sounds like you have not actually configured the current limit of your driver yet, that should be your first step. Measuring the voltage on the ref pin is one way to do this, but it sounds like you were doing something very wrong when you tried this with your now-damaged driver. Make sure you have your multimeter set to measure voltage, not current, when you look at the voltage on the reference pin. (My guess is that you were trying to measure current, and you effectively shorted the reference voltage output to ground through your multimeter; is this possible?) Another option is to set your multimeter to measure current and connect it in series with one of your stepper motor coils while the driver is in full-step mode and is not stepping (as described on the A4988 product page). Your goal should be to get the current limit close to 1 A, since that is what your stepper motor can tolerate, but note that you might have to decrease the current limit some (or add a heat sink) if the thermal protection starts kicking in (you will see the outputs start turning off intermittently).
Ok thanks Ben! You nailed it when you explained how I burnt up my last chip trying to test the current. I just did it the way you explained and got it set at 0.9A. The motor hisses a little but I think that might be normal or at least I hope so =). I do plan on putting heatsinks on them. Right now I am just using a very tiny one that sits on top, but I think I am going to make one that rises up a little and is as big as the whole driver board and then have a 12V fan blowing air on those.
I burnt up 2 of these now but I think I have it mostly figured out. I am going to order 2 more and a few other things so maybe they can be shipped out tomorrow.
Woo hoo I am getting excited seeing this come together!
