Audio Output Selection Courtesy Of The Internet

November 15, 2011 by Mike Szczys 37 Comments

[Peter] was tired of crawling behind his desktop computer to switch between headphones and speakers. We feel his pain, as the headphone port on our computer speakers has its own demonic hum rendering the jack useless to us. His solution was to build this output selector board, then control it via the network.

A relay is responsible for routing the single input to one of two outputs. One output is wired to the normally closed pin on the relay, the other to the normally open pin. The important thing here is to make sure you have a separate audio ground so as not to pick up noise from the rest of the hardware.

What you see above is only the switching circuitry. This is where [Peter] went a little overboard, using an Arduino along with an Ethernet shield to drive the relay via a transistor. For this particular application there must be an easier way. But if you’re working on home automation from your smart phone, this might be just the thing to make your audio setup browser-controlled.

[via Build Lounge]

The Origin Of The Arduino

November 15, 2011 by Jeremy Cook 17 Comments

If you ever wondered how the Arduino came into being, check out [IEEE Spectrum’s] article entitled “The Making of Arduino.” From it’s humble origins in Northern Italy, the Arduino, as shown by a large number of projects featured at [HAD], has become the go-to processor for DIY processing power. It’s cost (around $30) and ease-of-use are some of the biggest factors allowing it to become such a huge success.

One thing that interests many people about the Arduino is that it is totally open source, licensed under the Creative Commons License. This was quite innovative in itself since the CCL was generally applied to works of art like music and writing. Despite the fact that [Banzi] and his team decided to literally give the design away, 0ver 250,000 of these boards have been sold worldwide not including their many clones.

If you’re wondering how it got the name “Arduino”, it’s named after a bar named “Bar Di Re Arduino” in the Northern Italian town of Ivrea.

ColorNode: A Drop-in GE Color Effects LED Controller

November 13, 2011 by Mike Nathan 7 Comments

colornode-ge-color-effects-controller

[Paul] was looking to spice up his holiday decorations this year, so he picked up some GE Color Effects lights and started hacking away.

We’ve already seen how hacker-friendly these LED bulbs are, which is why [Paul] decided to give them a try. His ultimate goal was to synchronize several sets of lights from one location, which would unfortunately require that he run wires from his control board to each of the strings.

He then decided to go a different route, and build his own control board that would work as a drop-in replacement for GE’s controller circuitry. He wanted to retain the wireless control aspect of the lights, so he picked up some RFM12B wireless modules which happen to be well-supported by the folks at JeeLabs.

He modified their JeeNode board design to fit it in the Color Effects electronics enclosure, paring it back to the minimum components necessary to control his lights.

The hardware side of the ColorNode is complete, but the software is a work in progress. [Paul] says that once he gets things wrapped up, he will make the code available on his site.

Beginner Concepts: We’re Gonna Let You Finish, But First This Tutorial On Arduino Interrupts

November 8, 2011 by Jesse Congdon 13 Comments

OK, year-old pop culture references aside [Kyle] dropped us a line to show us his tutorial on using interrupts with your Arduino. Given the single core nature of your average Arduino’s AVR you pretty much have two choices for monitoring occasional un-timed inputs: Either check an input at an interval (which risks missing the signal entirely) or set up an interrupt to pause the chip’s normal operation. Obviously working with interrupts saves you tons of clock cycles since you are not polling a pin over and over. [Kyle] plans on a follow up tutorial to cover timer based interrupts, which can come in handy when generating frequencies and stuff.

Looking for more Arduino Basics? How about Basic on an Arduino. Check out our other beginner concepts posts as well if you need to work on your fundamentals.

Arduino-based MIDI Synth

November 8, 2011 by Mike Szczys 2 Comments

[Charles Gershom] has been tinkering around with his keyboard and Arduino in order to build his own version of a MIDI controlled synthesizer. It looks like he’s gutted the enclosure of some commercially available MIDI hardware to use for the project. This works nicely since it gives him both the MIDI and audio jacks that he needs. The box also provides a nice control surface where a set of four LEDs indicates the synth mode currently in use. There are also four potentiometers mounted on the panel, but they’re not yet up and running.

Check out the video after the break to see what this can do so far. [Charles] shows the device synthesizing sounds coming in from the keyboard. It is also used to playback the audio from Super Mario Bros. which is fed in by a music notation program on a computer. Only one voice is playing when this happens which makes us think this can only handle one channel at a time right now (but we could be wrong).

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A Simple Method For Expanding Arduino IO Capacity

November 8, 2011 by Jeremy Cook 52 Comments

Although there are other ways to do this, [Rod] has decided to write up his method of using two Arduinos and the I2C protocol to expand an Arduino’s IO capacity. As seen in the picture above, you’ll sacrifice 2 analog pins, but if you happen to need IO and have an extra Arduino lying around, this could really help. [Rod] also notes that this method could be used with many Arduino’s in parallel if the situation called for it. The code for this simple hack is included as well, so be sure to check out his site if you want to try this idea.

Some other solutions for extra IO would be to buy an Arduino Mega with 54 digital IO pins or the Muxshield which gives you 48 IO (and is stackable for other shields). An advantage of using the two Arduinos, is that if they are needed to be split in the future for different projects, this could be done. It’s good to have options for your IO needs as every hack is different.

Check out the video after the break to see everything being hooked up.

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G-35 Christmas Lights Do Make A Great LED Matrix

November 7, 2011 by Mike Szczys 16 Comments

This fully-addressable RGB LED matrix was built by [John Graham-Cummings]. He didn’t start from scratch, but wisely repurposed a strand of GE Color Effect lights and built a pleasant looking case in which to mount the G-35 hardware.

We’ve seen this hardware used in a similar way before. Because each ‘bulb’ has its own microcontroller, color data is shifted in via a serial bus. Orient the modules in any pattern you choose and account for that layout in software.

Since the strings have 50 bulbs, [John] simply cut off the one on the end to form his 7×7 matrix with the remaining 49 units. A square of plywood with a grid of holes holds each in place. Cord mess is not a problem as the extra was cut out and the remainders were soldered together again. [John] uses an Arduino Pro to feed in the data, which you can see for yourself in the clip after the break.

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