I am doing pretty well on the coding side and have managed to drive my 28BYJ-48 stepper motor using the
ULN2003 driver board through 4 pins both on an Arduino and on a photon. My problem is that I need to drive 3 of these independently and do not want to use 12 pins, especially since the Photon doesn't really have the space.
I found this diagram:
And here is the board:
but am a complete neophyte on building circuits. The questions I have are:
in5 and in6 are not used currently on the board, should I solder to the stubs?
out6 is not used on the board. In fact I don't even see a stub to solder to. Any ideas?
Am I correct that this circuit uses 4 1000 Ohm resisters?
Am I correct that the wire to the +5v (logic supply) should go to the Photon/Arduino?
Likewise, the +5-30v motor supply should go to the hot side of my external power supply?
Should I ground to the Photon/Arduino?
Alternatively to the questions above, should I pull the chip from the board and wire directly to it like the image shows?
Lastly, does anyone have a better way to handle this?
Thank you very much for any help provided. Based on my reading, this is an awesomely helpful community.
The diagram is wrong. That's a bipolar motor. However it's only wrong inside the "motor" circle and it probably will work for the unipolar motor you have. It would help if they labelled the wire colors or gave them numbers to help you hook it up.
By "stubs" you mean "pins"? It appears that not all the holes in1-in7 have pins in the holes. You should add or remove pins however you want. Sometimes it's easier to solder a wire onto a pin and sometimes it's better to have the wire go in the hole.
A better way would be to use a dedicated stepper driver. I've only used bipolar steppers so I don't have a good suggestion for what to use for a unipolar. If it's possible to cut the internal connection of the red wire between the two coils then it becomes bipolar and all the good bipolar drivers will work. A4988- or DRV8825-based units are both good for small steppers.
Thanks for the welcome Tom, appreciate it. I actually did read the "How to" post and thought I covered all my bases with a clear question, images, and description of the issue. For my future posting, where did I go wrong?
In answer to your questions, I was referring to the Particle Photon wifi IOT device.
I am building 2 different "Weasley clocks" and one will need 3 steppers to drive the hands and the other 5. I'm trying to lower the number of pins needed on either the Arduino Uno or the Particle Photon to drive the steppers. Also, the coding to control a stepper using 2 pins is much easier to write and execute, especially since I can leverage the existing stepper library.
MorganS:
The diagram is wrong. That's a bipolar motor. However it's only wrong inside the "motor" circle and it probably will work for the unipolar motor you have. It would help if they labelled the wire colors or gave them numbers to help you hook it up.
By "stubs" you mean "pins"? It appears that not all the holes in1-in7 have pins in the holes. You should add or remove pins however you want. Sometimes it's easier to solder a wire onto a pin and sometimes it's better to have the wire go in the hole.
A better way would be to use a dedicated stepper driver. I've only used bipolar steppers so I don't have a good suggestion for what to use for a unipolar. If it's possible to cut the internal connection of the red wire between the two coils then it becomes bipolar and all the good bipolar drivers will work. A4988- or DRV8825-based units are both good for small steppers.
The circuit diagram is from this site's reference section, in Libraries -> Steppers -> Circuits so it's interesting that it might not be correct.
Sorry for the bad nomenclature, I used "stubs" to refer to holes in the PCB that were filled with solder without a pin in them.
While the ULN2003 driver board I posted the pic of is a dedicated stepper driver board, it doesn't seem to give me what I need with regards to pins for the in and out side.
I did find a "How to" on converting these 28BYJ-48 steppers to bipolar so will look into the driver boards you mentioned to see if that's a more elegant solution. Thanks for that tip!
Hi,
Okay, by not enough space you mean not enough I/O pins.
Check and see if you can use the analog input pins a digital I/O.
OR.
You multiplex the control of 3 x 2003s, as the steppers are not being stepped every millisecond, they can do a "little dance step" on the minute and on the hour.
It should be possible to get three steppers to step sequentially in under a second, when the top of the hour occurs.
