Arduino Drives Seventeen Stepper Motors, Carefully

It’s fair to say that building electronic gadgets is easier now than it ever has been in the past. With low-cost modular components, there’s often just a couple dozen lines of code and a few jumper wires standing between your idea and a functioning prototype. Driving stepper motors is a perfect example: you can grab a cheap controller board, hook it up to a microcontroller, and the rest is essentially just software. But recently [mechatronicsguy] wondered if even that was more hardware than was technically necessary to get the job done.

It’s not that he was intentionally looking to make things more complicated for himself, of course. His rationale was entirely economic; if you’re looking to drive a dozen or more stepper motors, even the “cheap” controllers can add up. So he started to wonder if he could skip the controller entirely and connect the stepper motor directly to the digital pins of an Arduino. Generally speaking this is a bad idea, but if you’re careful and are willing to take the risk, [mechatronicsguy] is living proof it’s possible

So what’s the trick to running a whopping seventeen individual stepper motors directly from the digital pins of an Arduino Mega? Well, to start with you’re not going to be running the beefy NEMA 17 motors like you might find in a 3D printer. [mechatronicsguy] is using the diminutive (and dirt cheap) 28BYJ-48, a light duty stepper used in many consumer products. Even with this relatively tiny motor, you need to crack open the case and cut a trace on the PCB to switch it from unipolar to bipolar.

Beyond that, you need to be careful. [mechatronicsguy] reports he’s had success running as many as ten of them at once, but realistically the fewer operating simultaneously the better. This is actually made easier due to the relatively poor specs of the 28BYJ-48 motor; its huge eleven degree step size means its not really susceptible to the same kind of slippage you’d get on a NEMA 17 when powered down. This means you can cut power to all but the actively moving motor and be fairly sure they’ll all stay where you left them.

With as popular as the 28BYJ-48 stepper is, there are several projects this “quick and dirty” method of interfacing could potentially work with. This small “barn door” star tracker is an obvious example, but we’ve also seen some very nice robotic arms built with these low-cost motors which could benefit from the technique.

Arduino One Pixel Camera Sees All (Eventually)

Taking pictures in the 21st century is incredibly easy. So easy in fact that most people don’t even own a dedicated camera; from smartphones to door bells there are cameras built into nearly electronic device we own. So in this era of ubiquitous photography, you might think that a very slow and extremely low resolution camera wouldn’t be of interest. Under normal circumstances that’s probably true, but this single pixel camera built by [Tucker Shannon] is anything but normal.

Continue reading “Arduino One Pixel Camera Sees All (Eventually)”

Arduino Star Tracker Raises The Bar

Proving that astrophotography doesn’t have to break the bank, [Gerald Gattringer] has recently documented his DIY “barn door” style star tracker which is built almost entirely from scratch. Short of the Arduino and stepper motor, all the components were either made by hand or are standard hardware store finds.

The build starts with three aluminum plates which [Gerald] cut by hand with an angle grinder. He then drilled all the necessary screw holes and a rectangular opening for the threaded rod to pass through. He even used epoxy to mount a nut to the bottom plate which would eventually attach it to the tripod.

The plates were then roughed up and spray painted black so they wouldn’t reflect light. The addition of a couple of screws, nuts, and a standard hinge.

Motion is provided by a 28BYJ-48 stepper which is connected to the drive nut by way of a belt. The spinning nut is used to raise and lower the threaded rod which opens and closes the “door”. To control the motor, [Gerald] is using an Arduino Nano coupled with a ULN2003 Darlington array which live on a routed PCB he made with his school’s Qbot MINImill. While some might say the Arduino is unnecessary for this project, it does make the final calibration of the device much easier.

We’ve covered a number of similar star trackers here on Hackaday, including one that you crank by hand. But the professional looking final result really makes this build stand out.