IR Theremin Speaks In Four Voices

infraredTheremin

At the end of every semester, we get a bunch of cool and well-documented student projects from Cornell’s ECE4760 class. [Scott] and [Alex]’s infrared theremin is no exception.

The classic theremin design employs each of the player’s hands as the grounded plate of a variable capacitor in an LC circuit. For the pitch antenna, this circuit is part of the oscillator. For the volume antenna, the hand capacitor detunes another oscillator, changing the attenuation in the amplifier.

[Scott] and [Alex] put a twist on the theremin by using two IR sensors to control volume and pitch. The sensors compute the location of each hand and output a voltage inversely proportional to its distance from the hand. An ATMega1284P converts the signal to an 8-bit binary number for processing. They built four voices into it that are accessible through the push-button switch. The different voices are created with wave combinations and modulation effects. In addition to Classic Theremin, you can play in pure sine, sawtooth, and FM modulation.

If you’re just not that into microcontrollers, you could build this digital IR theremin instead. If you find IR theremins soulless or plebeian, try this theremincello.

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Automated Drink Mixer Is the Life of the Party

Hosting a New Year’s Eve party, but don’t want to be stuck behind the bar all night? You could set out a bowl or two of spiked punch, but where’s the hack? Free yourself from drink slinging duties with the Automated Drink Mixer created by Cornell University students [Justin] and [Austin]. Their design uses a 14″ diameter lazy Susan powered by a 12V bi-directional motor attached to a 2″ rubber wheel. The motor is capable of 70RPM, so the glass ultimately rides around at 10RPM. Orders are entered on a push-button menu. As this is a school project that should adhere to IEEE standards, all libations are non-alcoholic.

The software uses an overarching state machine, so the system polls for input from the menu at idle. When it receives an order, the lazy Susan rotates the glass to the right spout or series of spouts and then returns it to the starting point. [Justin] and [Austin] controlled the position of the glass with an IR emitter and phototransistor. This pair detects the black strips of tape around the edge which are spaced 60° apart. A comparator digitizes the signal and triggers an interrupt in the software, which counts the number of 60° slices. A full demonstration is waiting for you after the jump. Before you jump: drink responsibly, kids. If you aren’t up to that particular challenge, make yourself an alcohol-aware LED ice cube. If you need more LEDs in your life, whip up the Inebriator.

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Touching Conversations: Email Snippets Scroll By on Electro-Embroidery Piece

electroembroidery

[Wei Chieh Shih] really moves the needle when it comes to wearable technology. His textile design project entitled I Am Very Happy I Hope You Are Too is a striking marriage of masterful hand embroidery, delicate circuitry, and careful programming.

[Wei] is using an Arduino micro to drive a matrix of surface-mount LEDs in the Hello, World video, which is a ramp-up to the scrolling text version that’s in progress now finished. That full version is part of his residency project at Arquetopia in Oaxaca, Mexico and displays snippets of emails from his past relationships. It’s huge, with multiple matrices as large as 8×25 pixels!

No build notes could be found for this or any of [Wei]’s similar projects, like this awesomely dangerous 200 laser diode jacket or this eerily beautiful light installation on Taiwan’s north beach. Based on the pictures, our speculation is that he is using ordinary 6-strand embroidery floss to make stem or half cross-stitches on all the paths. He then runs very thin, flexible conductor underneath the channel of stitches and solders the wires to the component pads.

If [Wei] wants another way to wear his heart on his sleeve, he could investigate these dynamic LED clothing hacks.

Update: [Wei] has completed this project, and has more information available at his Behance site.

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New Contest: Win One of 20 Microchip Fubarino SD Boards

We had a blast with the Trinket Contest in October and November and can’t wait to see what you can come up with for this month’s competition. Microchip Technology is one of our advertisers and they offered us 20 Fubarino SD boards to give away as prizes. The challenge for you is to add our URL as an Easter Egg in your own microcontroller project. Rise to the top of our seemingly arbitrary system for picking winners and one will be delivered to your door for your future hacking pleasure.

Obviously we mean http://hackaday.com when we say URL, but what constitutes an Easter Egg? We figure it’s anything that is not apparently obvious in a piece of hardware. We built a quick example to get you thinking. Shown off in the clip after the break is a clock that displays our web address every day at 1:37pm. What did we pick that time? Because our clock displays in 24-hour time format and 13:37 is leet. See the code we used in our repo.

We thought of a few others, like making an embedded gaming that uses the Konami Code to reveal the Easter Egg, or a man-in-the-middle device that attaches to your keyboard and redirects your feeble attempts to load Facebook by closing the tab and opening Hackaday. The sky’s the limit with how creative these things can be!

Follow these rules to submit your qualifying entry:

  • You must somehow hide http://hackaday.com in your microcontroller project (embedded Linux doesn’t count unless you do some type of bare-metal programming)
  • Preference will be given to projects that are both clever and well documented. Notice we made a video, and posted code and an explanation of our project.
  • Write an email that has “[Fubarino]” in the title, includes the information on your documented entry, and lists your name and mailing address. Your name and mailing address will be used for shipping only and NOT for anything else. Emails should be sent to: contests@hackaday.com
  • Entries must be received before 12:00am Pacific time on 12/19/2013.
  • Employees and their families of Hackaday, SupplyFrame, and Microchip Technology are not eligible to win.

What are you waiting for? Dust off those chips and get hacking!

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Turbot is a Beam/Picaxe Hybrid

BeamBot

[James] wanted to build a BEAM turbot. He ran into some problems with the BEAM circuitry though, and ended up with a BEAM/Picaxe hybrid.
Beam robotics are the brainchild of Mark Tilden. The acronym stands for Biology, Electronics, Aesthetics, and Mechanics. BEAM based bots were very popular with hobbyists in the 90’s and early 2000’s, but popularity has since died down. BEAM robots tend not to use microcontrollers, instead attempting to simplify things down to the lowest number of elements.

[James’] turbot uses a miller solar engine. The original design used the engine to drive a Solar Turbot Latch. [James’] problem was that the photodiode “eyes” of the robot were not properly enabling the 74AC245 to pass current to the motor. Since the robot was built in a tiny space, debugging the circuit was extremely hard. After struggling with the ‘245 for some time, [James] decided to swich out the BEAM circuit for a Picaxe microcontroller.

The Picaxe can only sink or source about 20ma per pin, which is slightly less than the no load current of [James’] motors. To make up for this, he ganged up four pins per motor. There was some risk in the motors blowing up the Picaxe. However between the lightly loaded gearmotors and low current solar panels it seems to be working just fine.  Overall the bot is a very clean, compact build. Jump past the break to check out its really smooth crablike walking action.

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Explaining the low level stuff you don’t know about ARM programming

Most of us don’t realize how spoiled we are with the different development environments available on the internet. If someone wants to start a blank project on a new [ARM/DSP/…] platform, he usually fires up the dedicated Integrated Development Environment (IDE) and starts coding a C/C++ program. However, there are many initialization routines and scripts required with your program before it can run correctly. In his great article, [Andrew] explains to us what these are by starting a blank project without using any IDE.

As you can see in the above picture, [Andrew]’s project is made around an Atmel SAM4E microcontroller. The chosen toolchain is the arm-none-eabi-gcc from GNU Tools for ARM Embedded Processors. The first part of the article starts with a simplified explanation on how/why your code and variables are split into different memory sections (.bss, .data, .rodata, .text), then [Andrew] details how the linker script will put these sections at different physical addresses depending on your microcontroller’s memory layout. He also shows us how to take care of the stack placement, vector table, variable (non)initialization, and C Runtime. For information, the latter is executed when your processor starts, it is in charge of setting up the stack pointer, initializing the RAM, setting up the standard library and calling the main().

A very nice introduction on the very low level routines running on most processors out there.

Using 30 year old microcontrollers

chips

Like a lot of electronic tinkerers, [Andrew] has a lot of ancient components floating around his parts bin. His latest rediscovery in his cornucopia of components are a few Intel MCS-48 microcontrollers, dating back to 1977. Along with a few old EPROMs, [Andrew] decided it was worth getting these chips running again, if only for a historical curiosity.

[Andrew]’s had a few Intel 8035L microcontrollers on his hands, but this particular model of MCS-48 micros lacks any way to store code. This is where the EPROMs come in. With a modern EPROM programmer, [Andrew] was able to write some code to the extremely common for their vintage 27256 EPROMs. Erasing them, though, does require a UV lamp.

With the ROM programmed and the chips connected, [Andrew] was able to make a simple blinking LED circuit. Sure, it’s the simplest thing you can do with a microcontroller, but [Andrew]’s off to a great start in his explorations of older hardware.