The stepper said to not hold it by the wires, but it didn’t say to not do this!
@opsnlops Yes, works fine as long as there are no bugs in the software. Hah. I expected it to take off and rip the wires out of the protoboards. ;-)
@shuttersparks I wrote it in like 15 minutes, there can't be any bugs in something that small! 😅😂
@opsnlops Hah. Yes there can, but I get what you're saying.
My first experiments with steppers was in 1982. I had no plan, I was just curious. I used an MC6809 with some extra hardware.
Then I became curious whether I could increase the speed, the stepping rate, beyond the motor's ratings. I think it was a 12 volt motor. To do that you have to overcome the inductance of the coils and to do that you need higher voltage. But higher voltage would burn out the windings.
So I cobbled together a 48 volt power supply with some big Ohmite power resistors to limit the current. Rebuilt the transistor drivers. It worked. That motor screamed around nicely. The downside is most of the power is wasted as heat in the resistors.
Nowadays one could use MOSFETs in Class D and keep the efficiency high.
@shuttersparks Oh, I was totally joking! I'm sure it was full of bugs. :)
I've been experimenting with how fast I can send pulses to the stepper. 750us seems to be about as fast as I can go when it's in full step mode. Which seems slow to me, but that's really pretty quick!
@opsnlops Oh. Writing bug-free code is very do-able. I built much of my career on the ability to do that quickly. It can be done.
Yeah, the speed is limited by your power supply voltage and the inductance of the windings in the motor. The specs for the motor should indicate maximum stepping speed, and half-stepping speed.
@opsnlops Well, at least you've gotten your feet wet now. Any other steppers you acquire will be the same. All your knowledge applies.
It's been a while so I don't remember but 750 uS for a full step seems pretty damned fast. Small motors are faster, of course. They also make ones with minimal mass so they step faster, but the tradeoff is less available torque. I was working with pretty chonky ones the size of my fist. I want to say 250 full steps per second was about it for those. (Until I built my ridiculous power-wasting arrangement.)
Steppers are SO useful if you build machines. Definitely worth gaining experience with them.
@shuttersparks The loop is being driven in an ISR on a Pi Pico, so while I _can_ go as fast as 100us, that doesn't mean I want to. That's a lot of content switch very quickly.
@shuttersparks I think I need to by not-cheap motors that come with good data sheets. This one I'm messing with doesn't really say.
I've figured out that 750us is the limit for full steps, but it drops as I go to half and quarter steps. (Which makes sense.)
400 steps for one rotation is pretty good. I'm not sure that I'd ever need more than 400 (or maybe 800.)