Itchy: microcontroller

So, I have an arduino breadboarded to a stepper driver right now, and I’m staring at it, and thinking about how to control several of them. If I want tiny steps, I need to be able to switch different pins on and off, and I’m going to want tiny steps. That uses up a lot of pins.

I have two possible options. The hardware one is to have all of the driver speed pins run from one analogue pin, which I then run through a couple of comparators to get the level I want. That’ll give me output from one pin, but I do have to write out some logic tables and make the board more complicated.

The software method is to have three arduinos, slaved to a master computer (probably a Raspberry Pi by serial interface to the Pi GPio) and send the full movement to each, but screen it so that each Arduino only moves for its own movements, and hence can’t get out of step. (It could miss steps and not recover them, but that’s an issue to deal with in software, and I have ideas anyhow.)

The slot-in solution is probably a Reprap RAMPS controller, so I should look into that, but it’s extra money and a Pro Mini costs under a fiver, plus I have a couple hanging around.

I could /just/ manage a two-axis machine where I operate the z axis by hand and call the machine a plotter. That’s not likely to satisfy me, though. So, it’s time to talk with the programmer I’ve roped in – she’s going to know more than me about timings, multiple threads, and the like. She thinks I know what I’m doing. Don’t tell her!

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