HTML Based AVR Compiler Aims To Make Arduino Development On IOS Possible

April 10, 2012 by Mike Szczys 19 Comments

It’s surprising what lengths people will go to in order to bring functionality to their smart phones. In this case, [Tadpol] wanted a way to develop for his Arduino on an iOS device like an iPad or iPhone. He figures it’s possible to rewrite the IDE as HTML5, but since that’s a pretty large mountain to climb, he started by building a browser-based AVR compiler. It’s an interesting concept, and he’s got a working prototype up on Github for you to test. Perhaps you can throw your hat in the ring and help him with development?

The web interface uses boxes to add to the code. What you see above is three sets of commands which will blink an LED. The project, named Avrian Jump, uses a simple ladder language to feed the compiler, with several different options for output. The most interesting in our mind is a WAV file which can be used to program an AVR from the audio out of your device. That would make programming as simple as connecting the specially modified AVR to your headphone jack. There’s also an ASCII output which allows you to save your programs for later alteration, S19 output for AVRdude programming, and an assembler output for debugging purposes. It’s hard to see where this project might go, but we have to admit that the concept is intriguing.

Playing Chiptunes With A YM2149 And Optimizing An Arduino

April 10, 2012 by Brian Benchoff 19 Comments

[Oryx] grew up with the bleeps and bloops of an Atari ST, so it comes as no surprise he would want to relish in his nostalgia by playing with the YM2149 sound generator he recently picked up on eBay. Like most of us, [Oryx] went to his old standby, the Arduino, when it came to connect this bare chip to his computer. The first circuit didn’t work, so after a lot of poking around the firmware, [Oryx] discovered the benefits of hand-optimizing software.

There are a lot of sound files available for the YM2149 floating around on the Internet. These files are just dumps of the 16 registers at 50Hz, so it’s very easy to send these from a computer to an Arduino over a serial connection. Unfortunately, when [Oryx] got his breadboard set up nothing happened. After breaking out the ‘scope, he discovered the Arduino was switching pins 100 times slower than the YM2149 data sheet called for.

[Oryx] remembered seeing a great blog post going over the speed at which the digitalWrite() function changes pin states. We’ve seen this before, and the fastest way to change pin states on the Arduino is with the ugly bitwise manipulation. After changing a few lines of code, [Oryx] was switching two pins nearly simultaneously.

Now that the YM2149 chip is working correctly, [Oryx] is planning to make a MIDI synth out of his project. You can get an idea of how that will sound with the demo video he put up after the break.

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Measuring The Capacities Of Different Battery Brands

April 9, 2012 by Brian Benchoff 51 Comments

Being the smart consumer he is, [Denis] usually looks at the price per pound when comparing similar products at the grocery store. When it came time to buy a few AA batteries, he didn’t have any data to go on. To solve his little conundrum, [Denis] decided he would test several brands of batteries and see which one gives him the most bang for the buck.

After bringing home a haul of a dozen different brands of AA cells, [Denis] broke out the Arduino and starting designing a circuit. To test how much energy each brand provides, the Arduino measures the voltage across a load every second until the battery reaches 0.2V. The elapsed time, as well as the voltage, Watt hours, Joules, and ambient temperature are logged on an attached LCD screen and sent over a USB serial link to automate the data collection process.

What’s the verdict? Unsurprisingly, words like ‘super,’ ‘max,’ and ‘ultra’ didn’t connotate a better battery. The best bang for the buck came from an off-brand called RS Power Ultra. The worst battery was the Panasonic Evolta cells that came in at about $1.50 USD per watt-hour.

If you’d like to verify [Denis]’ work, all the code is up on Github along with the schematic.

A Simple Project To Get You Started With The Android ADK

April 6, 2012 by Mike Nathan 9 Comments

simple-adk-exercise

If you just got your hands on a shiny new Android phone and are looking for a fun project to try out, you might want to check out this simple Arduino exercise that [Mike Mitchel] put together. Everyone needs a starting off point for hacking, and [Mike] thought that combining and Arduino and Android handset together for the purpose of temperature sensing and light metering would be a great place to begin.

The prerequisites for this project are a bit beyond a simple breadboard and a few ICs, requiring an $80 Android ADK board to go along with your phone and Arduino. If your focus is going to be on interfacing your phone with microcontrollers however, it’s purchase you’ll make sooner than later anyhow.

The setup is pretty simple as you might expect. A photocell and TMP36 temperature sensor are connected to the Arduino, then with a bit of code and USB host magic, the Android app shows the temp and amount ambient light present in the room.

[Mike] has made all of his easy to read and well commented code available online, so be sure to check it out if you have been thinking about (but putting off) playing around with the Android ADK.

Quick And Easy Arduino-powered Theremin

April 5, 2012 by Brian Benchoff 19 Comments

[Martin] sent in a great guide to a simple Arduino based theremin. It’s a very small build – just a single common IC and some passive components – and easy enough to build in an afternoon.

The theremin is based on a simple LC oscillator built around a 7400 quad NAND gate IC, a wire antenna, and a few caps and resistors. When a hand moves closer to the antenna, the frequency of the oscillator increases; when a hand moves away, the frequency decreases. On the software side, the oscillator is connected to the internal hardware counter of the Arduino. Every time there’s a change in the voltage output by the oscillator (all the time, varying slightly with the distance from a hand to the antenna), the counter increases by one. This counter is tallied up over 1/10th of a second, and the distance from the instrumentalist to the theremin can be determined. From there, it’s just outputting a frequency to a speaker.

All the code, schematics, and board layouts are available on [Martin]’s guide, and most of our readers probably have the parts to build this lying around their workbench. You can check out a video of [Martin]’s theremin in action on his guide.

Make Your RC Car Drive Itself With This Simple Brain Swap

April 4, 2012 by Mike Nathan 13 Comments

arduino-rc-conversion

If the kids have lost interest in that RC car or truck you bought them over the holidays, [Randy Sarafan] from Instructables has a few ideas that might help make the toys fun again, while teaching your kids a bit about electronics in the process. In his writeup, he shows how to swap out the brains of your run of the mill RC truck, enabling it to do far more than was originally intended. The procedure is pretty simple, and something that you can easily involve your kids in, if you’d like.

He uses an Arduino and a motor shield to keep the conversion simple, but this can be done with just about any capable microcontroller you might have on hand. [Randy] added a Parallax Ping sensor to the front of the truck enabling it to avoid objects as it drives itself, but since he cut out the truck’s original control board we’re assuming that there’s no way to override the truck’s actions at present.

[Randy] calls the conversion a “robot” though it seems like more of a semi-autonomous rover if you ask us. Regardless, revamping an old RC car is certainly far better than letting it collect dust on a shelf, or worse, tossing it out during spring cleaning.

Continue reading to see a short video of [Randy’s] RC truck in action.

[via HackedGadgets]

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Auto-locking Pet Door Ensures That Your Outdoor Kitty Obeys Its Curfew

April 4, 2012 by Mike Nathan 26 Comments

If you’ve got a pet that roams freely in and out of your house, you may find yourself wanting to more closely regulate how they come and go. [tareker] was looking to keep his cat indoors at night when dangerous animals might be lurking in the neighborhood, but he didn’t want it to become a hassle.

He already had locking pet door on hand, which he hacked to regulate the egress and ingress of his cat automatically. He installed a pair of reed switches to determine if the door had been opened outwards (cat leaving) or inwards (cat returning), keeping track of the state using an Arduino Nano. A servo motor attached to the door’s frame locks the door whenever it detects the cat is safely inside after nightfall.

While he also added an RGB LED to reflect the status of the door, he’s considering connecting it to the Internet so that he can control and check the door from wherever he might be at the moment.