Arduino Hacks

3037 Articles

Sandwich Robot Keeps You Fed So You Can Keep Hacking

November 27, 2016 by 16 Comments

Food. A necessary — often delicious — interruption of whatever project you’re currently hacking away at. Ordering takeout gets expensive and it’s generally unhealthy to subsist solely on pizza. With the Sandwich-O-Matic, a simple voice command fulfills this biological need with minimal disturbance of your build time.

Built for a thirty-six hour hackathon, the Sandwich-O-Matic is controlled by a Photon and an Arduino. The backend is running node, hosted on AWS, and Google Cloud was used for voice to text recognition. This thing is a fully automated and voice controlled sandwich building station. A DC motor services the toaster, while the rest of the device is actuated by servos. Simply tap the ‘begin recording’ button on the site, tell it your ingredient choices, and off it goes.

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A Dual-purpose Arduino Servo Tester

November 23, 2016 by 8 Comments

RC flying is one of those multi-disciplinary hobbies that really lets you expand your skill set. You don’t really need to know much to get started, but to get good you need to be part aeronautical engineer, part test pilot and part mechanic. But if you’re going to really go far you’ll also need to get good at electronics, which was part of the reason behind this Arduino servo tester.

[Peter Pokojny] decided to take the plunge into electronics to help him with the hobby, and he dove into the deep end. He built a servo tester and demonstrator based on an Arduino, and went the extra mile to give it a good UI and a bunch of functionality. The test program can cycle the servo under test through its full range of motion using any of a number of profiles — triangle, sine or square. The speed of the test cycle is selectable, and there’s even a mode to command the servo to a particular position manually. We’ll bet the build was quite a lesson for [Peter], and he ended up with a useful tool to boot.

Need to go even further back to basics than [Peter]? Then check out this primer on servos and this in-depth guide.

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A Buck-Boost Converter From The Ground Up

November 22, 2016 by 17 Comments

DC to DC conversion has come a long way. What was once took an electromechanical vibrator and transformer has been reduced to a PC board the size of a largish postage stamp that can be had for a couple of bucks on eBay. So why roll your own buck-boost converter for the ground up? Maybe because sometimes the best way to learn is by doing.

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DIY Talkie Toaster from Red Dwarf

Red Dwarf’s Talkie Toaster Tests Tolerance

November 21, 2016 by 10 Comments

In the Red Dwarf TV series, Talkie Toaster wants to know if you want toast, and if not toast, then maybe a muffin or waffle, and it will pester you incessantly until you smash it with a 14lb lump hammer and throw it in a waste disposal. Now [slider2732] has actually gone and made one of the infernal machines!

He’s hidden a PIR sensor in the toaster handle to tell an Arduino Pro Mini when someone is unfortunate enough to be passing by. The Arduino then reads sound files from an SD card reader and plays them through a 3 watt amplifier out to a speaker. For that he uses the TMRpcm library available on github.

[slider2732] cleverly mounted the speaker to the side of the toaster along with some appropriately shaped bits and pieces, and some LEDs to make it appear and work much like the circular panel that lights up on the real Talkie Toaster. We dare you to watch the video after the break, unless you really are looking for toast. As a consolation, the video also walks through making it.

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EMG Tutorial Lets You Listen To Your Muscles

November 20, 2016 by 6 Comments

What with wearable tech, haptic feedback, implantable devices, and prosthetic limbs, the boundary between man and machine is getting harder and harder to discern. If you’re going to hack in this space, you’re going to need to know a little about electromyography, or the technique of sensing the electrical signals which make muscles fire. This handy tutorial on using an Arduino to capture EMG signals might be just the thing.

In an article written mainly as a tutorial to other physiatrists, [Dr. George Marzloff] covers some ground that will seem very basic to the seasoned hacker, but there are still valuable tidbits there. His tutorial build centers around a MyoWare Muscle Sensor and an Arduino Uno. The muscle sensor has snap connectors for three foam electrodes of the type used for electrocardiography, and outputs a rectified and integrated waveform that represents the envelope of the electrical signal traveling to a muscle. [Dr. Marzloff]’s simple sketch just reads the analog output of the sensor and lights an LED if it detects a muscle contraction, but the sky’s the limit once you have the basic EMG interface. Prosthetic limbs, wearable devices, diagnostic tools, virtual reality — the possibilities are endless.

We’ve seen a few EMG interfaces before, mainly of the homebrew type like this audio recorder recruited for EMG measurements. And be sure to check out [Bil Herd]’s in-depth discussion of digging EMG signals out of the noise.

3D Printed Moon Phase Clock

November 19, 2016 by 20 Comments

Someone once observed that the moon is a harsh mistress. But that doesn’t mean you can’t keep track of her, specially with this awesome moon phase clock that [G4lile0] designed and built.

It uses a 3D printed moon model combined with a series of LEDs to create the phases. These LEDs are driven by an Arduino that calculates the phase to show, as well as driving a small OLED display that shows the date and time. There is even a party mode for all of those lunar raves that you host.

[G4lile0] has done an excellent job of documenting the code that drives the lamp, so it would be easy to add features, or adapt this design to show the phases of another moon or add other features. It’s an excellent overall design, and kudos to [G4lile0] for doing it all with open source tools like FreeCAD.

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Only One Button? No Problem!

November 18, 2016 by 26 Comments

Sometimes less is more. This is especially true when dealing with microcontrollers with limited I/O pins. Even if you have lots of I/O, sometimes you are need to pack a lot into a little space. [Hugatry] was inspired by the simple interface found on a lot of flashlights: one button. Push it and it turns on. Push it again, and it switches modes. You cycle through the modes until you finally turn it back off. One button provides mutliple functions. The question is how can you use a power switch as an I/O device? After all, when you turn the power off, the microprocessor stops operating, right?

[Hugatry’s] answer is quite simple. He connects a resistor/capacitor network to an I/O pin (or multiple pins). When the processor turns on initially, the pin will read low and the capacitor will charge up. If you turn the power off, the CPU voltage will fall rapidly to zero, but the voltage on the capacitor will discharge slower. If you wait long enough and turn the power on, there’s no difference from that first power on event. But if you turn the power on quickly, the capacitor voltage will still be high enough to read as a logic one.

What that means is that the processor as part of its start up can detect that it was recently turned off and take some action. If it remembers the previous state in nonvolatile memory, you can have the code cycle through multiple states, just like a flashlight. You can see a video of the setup, below.

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