arduino

2927 Articles

An Arduino Power Inverter

June 21, 2013 by 32 Comments

If you’ve got a few solar panels lying around, or even if you want some 120/230 V AC power from a few 12 Volt batteries, you’ll need a power inverter. Sure, you can drop on down to any big box store and pick one of these up, or you can be like [Michael] and build your own (Danish, translation).

[Michael] found himself in the possession of a few halogen light transformers and decided to make use of them by building a DC to AC power inverter. The inverter is fairly simple – just the transformer, a few MOSFETS, and an ATMega0168 for software control that includes a ‘soft start’ feature that prevents power surges on startup.

The circuit is simple enough to etch at home, although a soldermask and a nice insulated enclosure would probably be ideal for this application.

Giving An RC Tank A Fire Control Computer

June 11, 2013 by 29 Comments

tank

[Vincent] plays around with remote control tanks, and even though his current model is a WWII-era armor piece, he’d still like modern accoutrements such as a fire control computer and laser sighting for his main gun. His latest project did just that (French, Google translation) with the help of an Arduino, a few modifications to the receiver, and an IR rangefinder.

The stock RC tank includes servos to move the turret and the requisite electronics to fire an Airsoft gun. The precision of the mechanical movements inside the turret weren’t very precise, though, so [Vincent] had to gear down the servos to turn large movements into slight adjustments. After that, he installed an IR rangefinder and laser diode onto the barrel that allowed the gun to sight a target and read its distance.

After some experimentation with the rangefinder and laser, [Vincent] plotted data from firing a few BBs at a whole bunch of distances and targets. The graph came out fairly linear, and after plugging this into a graphing calculator, he was able to find an equation that took into account the distance and angle so the Arduino-powered fire control computer would hit its mark.

The accuracy of the gun is very impressive, all things considered. [Vincent] is able to accurately fire BBs downrange and hit an 8×12 cm target at five meters. You can check out that action below.

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Apple MagSafe Protocol Hacking

June 7, 2013 by 4 Comments

[Ken Shirriff] was interested in how the Apple MagSafe works. Specifically he wanted to know what controlled the LED on the connector itself so he tore one open to see what is inside. There’s a chip present and he didn’t waste time figuring out how the MagSafe communication protocol works.

The DS2413 chip he found on the MagSafe’s tiny little PCB has just six pins. Two of these control a pair of LEDs, which give the indicator its color range.  Another pin is used for 1-wire communications. When polled the charger will return a 64-bit identification number that includes a variety of information. [Ken] looks into what data is offered from several different models of charger by using the Arduino setup above. But the results are not entirely straight-forward as he discusses in his article. The 1-wire protocol is also used to switch the LEDs. This process is the responsibility of the computer being charged, but [Ken] shows how the colors can be cycled using an Arduino (with a couple of 9-volts as a source instead of a connection to mains).

Quick And Dirty Touch-sensitive Keyboard Project

June 3, 2013 by 8 Comments

quick-dirty-touch-sensitive-keyboard

You don’t have to have high-quality parts to play around with electronics and here’s a great example. [Vishal] used junk to play around with CapSense, the touch sensitive Arduino library. What he ended up with is this touch-based piano keyboard.

We’ve featured the CapSense library in the past, but even that example uses a very meticulously crafted test rig of foil tape, protoboard, and some resistors. If you still haven’t given it a try follow this example of using aluminum foil, electrical tape, and a cardboard box.

[Vishal] just sandwiched the end of jumper wire between two pieces of foil to make each ‘key’. We believe the other end of the wire is soldered to the bias resistors where they connect to a couple of pin headers. The headers were hot-glued in place through holes in the bottom of the box, making the entire rig simple to plug into the Arduino board driving it. After adding in a small speaker and flashing the code he’s finished. It certainly makes for a short afternoon project which you won’t feel bad about taking apart later since you didn’t sink a ton of time or resources into the build.

Benchmarking USB Transfer Speeds

June 3, 2013 by 46 Comments

boards

[Paul Stoffregen], creator of the Teensy series of microcontroller dev boards, noticed a lot of project driving huge LED arrays recently and decided to look into how fast microcontroller dev boards can receive data from a computer. More bits per second means more glowey LEDs, of course, so his benchmarking efforts are sure to be a hit with anyone planning some large-scale microcontroller projects.

The microcontrollers [Paul] tested included the Teensy 2.0, Teensy 3.0, the Leonardo and Due Arduinos, and the Fubarino Mini and Leaflabs Maple. These were tested in Linux ( Ubuntu 12.04 live CD ), OSX Lion, and Windows 7, all running on a 2012 MacBook Pro. When not considering the Teensy 2.0 and 3.0, the results of the tests were what you would expect: faster devices were able to receive more bytes per second.  When the Teensys were thrown into the mix, though, the results changed drastically. The Teensy 2.0, with the same microcontroller as the Arduino Leonardo, was able to outperform every board except for the Teensy 3.0.

[Paul] also took the effort to benchmark the different operating systems he used. Bottom line, if you’re transferring a lot of bytes at once, it really doesn’t matter which OS you’re using. For transferring small amounts of data, you may want to go with OS X. Windows is terrible for transferring single bytes; at one byte per transfer, Windows only manages 4kBps. With the same task, Linux and OS X manage about 53 and 860 (!) kBps, respectively.

So there you go. If you’re building a huge LED array, use a Teensy 3.0 with a MacBook. Of course [Paul] made all the code for his benchmarks open source, so feel free to replicate this experiment.

Hardware Store Robot Hand

June 3, 2013 by 12 Comments

hardware-store-robot-hand

Here’s a robot hand which can be built using mostly hardware store items. It doesn’t have the strongest of grips, but it does have lifelike movement. The demonstration video shows it picking up small objects like a metal nut.

The image above shows the ring and pinky fingers of the hand beginning to flex. These are controlled by the servo motors mounted in the palm area. The skeletal structure of each digit begins with the links of a bicycle chain. The links are first separated by removing the friction fit rods. Each rod is replaced with a screw and a nut, which also allows the springs (which open the digits) to be anchored at each ‘knuckle’.

[Aaron Thomen] didn’t stop the design process once the hand was finished. He went on to build a controller which lets you pull some rings with your fingers to affect movement. This movement is measured by a set of potentiometers and translated into electrical signals to position the hand’s servo motors. The demo, as well as two how-to videos are embedded below.

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Arduino-compatible, Quad-core ARM Dev Board

June 1, 2013 by 36 Comments

The Advent of the Raspberry Pi has seen an explosion in the market for ARM dev boards, sometimes even with pinouts for Arduino shields. The UDOO, though, takes those boards and ramps up the processing power for some very, very interesting builds.

The UDOO comes equipped with a dual or quad-core ARM CPU running at 1GHz with 1 GB of RAM. Also on board is the Atmel SAM3X8E – the same chip in the new Arduino DUE – and has pinouts for all those Arduino shields you have lying around.

In addition to serving your next project as a souped-up Raspberry Pi, UDOO also includes 78 (!) GPIO pins, Gigabit Ethernet, a camera connector, one SATA port (on the quad-core version), and an LVDS header for attaching LCD monitors. Basically, the UDOO is the motherboard of an ARM-powered laptop with the pinouts to handle Arduino shields. It’s just like [Bunnie]’s laptop, only this time you can actually buy it.

The UDOO doesn’t come cheap, though: on the UDOO Kickstarter, the dual-core version is going for $150 while the quad-core is priced at $170. Still, if you need the power to run a pair of Kinects or want to build an awesome torrent box, you’d be hard pressed to find a more powerful board.