Stepper wire order

[brad-colbert]

Nik,

Fantastic project! Wow!

I have a question about the wire harnesses for the steppers.

I ordered the shorter wires but I don't understand the wire order issue. Is it that the wires order need to be swapped?

The long wires that came with the steppers have dupont connectors on the driver side, so the order could be whichever way I insert the connector, so I guess they are "ambidextrous"

Thank you!

[nikivanov]

Hey Brad!

The easiest way is to look at the wire that came with the motor and trace the order of wires on both ends. Like the leftmost wire on driver is is also leftmost on the motor. 2nd from the left is rightmost (for example) etc. you need to repin the short cable to match. Whether you repin on motor or driver side doesn't matter. If that's still confusing, look up the motor spec and the labels on the driver output - 1A 1B 2A 2B should match.

[brad-colbert]

Hi Nik,

The problem I have is that the connector for the wire that came with the motor for the driver side is a Dupont connector so it can go into the driver either direction. There aren't pins to ensure that the wires end up in any specific order.

[nikivanov]

@brad-colbert could you please take a picture of your motor, driver, and wire?

[brad-colbert]

Sure thing and thank you!
The dupont is what came with the motor. The white one is the short one.

[brad-colbert]

Not a great picture of the motor. Not sure what to do there.

[nikivanov]

So the cable that came with your stepper is 4pin to 4 pin but the motor has 6 pins? I'm not sure what's going on here but the cable in question is just of the wrong type

[brad-colbert]

I think this will help.

They both go from 4 to 6. It looks like the order is the same so I think they are good? (Good said with a shrug)

[brad-colbert]

A little AI tells me:

So the extra two pins would normally be the center taps for the two windings. Those are useful for unipolar stepper drivers, where the driver energizes half of a winding at a time.

For modern 3D-printer/CNC-style drivers — A4988, DRV8825, TMC2209, etc. — you use the motor as a bipolar 4-wire stepper and leave the center taps disconnected.

I've run into this before but those brain cells are dead by now. I could just hook it up as is. Worse case the spindle doesn't turn? (famous last words)

[nikivanov]

The shorter cable is exactly what you need. You can try the pin out in the video first - it should work. If not, look up motor pin specs and match the coil pins with the driver board.

[brad-colbert]

I'll give it a go and try to report back. Could be good info for others in the future.

[brad-colbert]

Hi Nik,

Thanks again for an awesome project!

Getting back to the build. I have it all together but not getting any action out of the steppers. Can you provide a little guidance on where I might or should focus the debugging? I have a small oscilloscope. Would it be proper to first scope the pins where the drivers hook up to the ESP32? Then move toward the steppers at each junction?

[brad-colbert]

I wonder if this is my problem:

[nikivanov]

I can confirm that my boards have resistors, so that very well might be your problem. As far as wire ordering goes, look at your photo above - you can see pins 2B 2A 1A 1Bon the right side of the controller. On the other side of the board, you can see the traces go to the above white JST connector. The stepper spec document shows you those same pins here (https://www.omc-stepperonline.com/index.php?route=product/product/get_file&file=2726/17HE08-1004S_Full_Datasheet.pdf). Just match the pins with the short wire you have

[brad-colbert]

Hi Nik,

Oh, mild progress. I soldered on two resisters (poorly) in the spots that were missing. I now get a little "action" from the steppers. They jiggle back and fourth when I use the UI to enable them.

Thoughts?

[nikivanov]

No clue, sorry. Your best bet is to buy the driver breakout boards from a different seller and hope for the best.