Panic question: Controlling DC motors with a Stepper Driver L647x

Hmm, after nuking my motor controller and needing some spare parts seriously for a deadline I am desperate to come up with solutions with existing hardware.

Would it by any chance be possible to control 2 dc motors with a stepper motor driver. This one to be exact: [url][/url]

As I understand the stepper its two coils inside the motor that needs fast changing currents. What if these currents are held at 0Hz?

@ njbuch - You poor guy. Nope not possible.

EDIT: Hang on. I’ve never even attempted it… Theoretically it is possible, but you will have to set the EL_POS registers.

@ njbuch, do you need to change the speed of the motor? If not why not just use a relay for now.

you can use GHI’s relay module, and hook them up like the attached.

ignore the NUD3112LT1G’s, that is just there to simply say dont drive them directly from a port pin.

@ VersaModule - Thanks a lot, I have been thinking about something along those lines, but was afraid that I could not change the two direction changing relays (RL1 and RL2) at the same time, and then there was a risk of shortcutting something. Is that not a risk in this?

@ njbuch, If you are unable to take a port pin to drive both relays at the same time you are still fine. There is no risk of shorting anything out.
So your are totally fine when it’s time to switch directions by opening RL3, then change stare of RL1 then RL2. The way I have it wired here is all good and safe.

Just an FYI… If say you do not first open RL3, before you change either RL1 or RL2 then what will happen is that it will short the motor leads.
All this will do is make you motor act like it has a brake on it. For instance, say you put some sort of metal wheel on the motor shaft. You turn it on and it spins up the wheel. If you open RL3 to disconnect the power to it lets say it takes 30 seconds to spin down. Now, when it comes time for you to change directions, if you done first open RL3, and change either RL1 or RL2 it will basically tie the motor leads together and make it come to a very fast stop. This same “brakeing” is what they do on many RC cars to quickly stop them.

Hope that all made sense the way i worded it all.

@ VersaModule - Thanks for that clarification - VERY helpful, I feel ready to start playing with lots of wires to connect that many relays. Will post my results…

Thanks all! :slight_smile: