Electronics > Beginners
Manual Stepper Motor Control (No Arduino)
rstofer:
Some years back I helped a fellow build this kind of mount using a PIC microcontroller.
In his case, he used a potentiometer to control the rate of stepping. This is pretty easy using an analog input of the Arduino but is not a preferred method, apparently.
This project steps the barn door at 15 degrees per hour. That fixed number is precomputed and is part of the code. The only thing missing in the project, that I can see, is a fast step to get on target. I would probably add a '+' and '-' button to step in each direction at some high rate. In fact, I might also add a potentiometer to control the rate of high speed stepping. But that's a refinement for another day.
https://petapixel.com/2018/05/15/how-i-built-a-star-tracker-for-dslrs/
There are only 10 lines of code - total! Plus downloading and installing the CheapStepper library from GitHub
https://github.com/tyhenry/CheapStepper
Note that the author of the mount goes into considerable detail on alignment, giving 2 different methods of getting the hinge axis aligned with Polaris.
Sikorsky66:
I cant reprogram an Arduino in the Canadian wilderness in temperatures so cold the cameras have to have hand warmers taped to them to keep them from shutting down. This needs to be as simple and robust as possible.
Could you please recommend a stepper driver that will work.
jmelson:
--- Quote from: Sikorsky66 on January 30, 2020, 08:53:22 pm ---I cant reprogram an Arduino in the Canadian wilderness in temperatures so cold the cameras have to have hand warmers taped to them to keep them from shutting down. This needs to be as simple and robust as possible.
Could you please recommend a stepper driver that will work.
--- End quote ---
The A4988 available from all over the world as "Pololu compatible" do quite nicely. They run most any small 4-wire stepper and have microstepping and step and direction inputs.
Jon
donotdespisethesnake:
--- Quote from: Sikorsky66 on January 30, 2020, 08:53:22 pm ---Could you please recommend a stepper driver that will work.
--- End quote ---
There isn't one meeting your requirements. You have chosen a set of components which make your task impossible. :-//
OTOH, your goal is very simple to achieve if you chose the right components, even if you don't want to use a microcontroller. There is no need to reprogram Arduinos in the wilderness, don't know where you get that idea.
You could build some hardware using TTL logic to drive the stepper, you might even find a way to incorporate the PWM driver. Basically you need a 555 to generate a clock and some logic to drive the right order of signals.
brucehoult:
--- Quote from: Sikorsky66 on January 30, 2020, 08:53:22 pm ---I cant reprogram an Arduino in the Canadian wilderness in temperatures so cold the cameras have to have hand warmers taped to them to keep them from shutting down. This needs to be as simple and robust as possible.
--- End quote ---
Why on Earth would you reprogram it?
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