GSM Modem Means Wireless Serial Connections

April 6, 2012 by Brian Benchoff 33 Comments

By now, most of us have seen have seen one of those GSM to wi-fi hotspot bridges. They’re interesting devices, and being able to carry a small wireless router with you at all times is very handy. Surprisingly, we haven’t seen many builds featuring these portable wireless hotspots, something probably due to the effort in breaking out a serial connection on these devices. The people at Open Electronics decided to build their own small serial-enabled cell phone modem, a boon to someone wanting a serial connection to any place with a cell tower.

The Open Electronics GSM/GPRS/GPS modem includes a header for an FTDI USB serial chip and a GSM module. Plug one into your computer and after a few short commands into a terminal, you’ve got a serial connection to nearly anywhere in the world.

The cost of the setup is a little high – around 80€ or $100 USD – and you probably should buy more than one so you can also receive data. While it is more expensive than the XBee wireless boards we see often, this GSM modem isn’t limited to the 300 foot range of the XBee. We’ll probably see this in a high altitude balloon before too long.

Displaying Bubbles In Mineral Oil

April 6, 2012 by Brian Benchoff 15 Comments

After he saw a ‘falling water display,’ [Matt] figured he could turn that idea on its head. He built a display that uses bubbles for pixels. Even though the build isn’t complete, we love the results so far.

[Matt] began his build constructing a tall, thin water tank out of acrylic. Eight solenoids were mounted in the base of the tank, attached to an aquarium air supply, plastic tubing, and one way valves. The first run of the bubble display didn’t go too well, but after adding dividers between each column the display started working.

With the dividers, [Matt] no longer had to worry about bubbles colliding or moving any direction but up. The bubbles weren’t moving consistently, so he replaced the water with mineral oil. Oil made a huge improvement, but the bubbles still float up at different speeds. [Matt] ascribes this to the unregulated air supply, but we’re thinking this problem could be mitigated with glycerine like the previous bubble display we saw.

It may still have some problems, but we love the result. Check out the video of bubbles in mineral oil after the break.

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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.

The Best LED Cube Build We’ve Seen

April 6, 2012 by Brian Benchoff 28 Comments

[Nick] wrote in telling us about the LED cube he built over the course of six months. He calls LED cubes ‘done to death,’ but [Nick] might be too humble. His 8x8x8 RGB LED cube is the best we’ve ever seen.

To start his build, [Nick] built a simple 4x4x4 cube as a proof of concept. The baby cube worked but the fabrication process got him thinking. Instead of building his monster LED cube in layers from the bottom up, he would need to build columns from left to right. After the construction of a jig, soldering eight panels of 64 LEDs, and buying a new soldering iron tip, [Nick] had a beautiful assembled LED cube. The only thing missing was the electronics.

Most of the LED cubes we’ve seen use the TLC5940 LED driver for hardware PWM, [Nick] decided to go with the simpler but more familiar STP16 chip. After hooking up his huge LED driver board up to a chipKIT Uno, the 80 hours of programming began.

In the end, [Nick] built the best LED cube we’ve seen (even though it isn’t the largest) and put together one of the best build logs in recent memory. Because no LED cube build is complete with out a video there’s an awesome demo after the break.

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Digital Speedometer With An Arduino

April 5, 2012 by Brian Benchoff 25 Comments

[Martyn] is restoring a 32-year-old Honda motorcycle, so when the ancient speedometer broke last year he thought it was prime time to start of a digital speedometer project. We’re loving the results so far, and would love seeing it on a nicely restored bike.

Instead of the relative horror of driving 40 LEDs with a single Arduino, [Martyn] bit the bullet and got a Maxim 7221 LED driver. Controlling 64 LEDs over a three-wire interface simplified the board design somewhat, allowing [Martyn] to etch his own PCB with the toner transfer & HCl/H2O2 method. To actually power and control the entire circuit, [Martyn] used an Arduino loaded up with a program based LedControl library makes programming the spedometer a snap.

Although the speedo works, [Martyn] says he isn’t proud of how it looks. We don’t mind – the candy colored jumpers add a nice flair to the project, and they’re hidden behind the face plate of the speedometer. We’re sure once he gets the neutral, high-beam, and warning indicators working with the LED bar array / tachometer, everything will look awesome.

via reddit

Reverse Engineering A Futaba SBUS Remote Control

April 5, 2012 by Brian Benchoff 18 Comments

In the world of model aircraft, Futaba’s SBUS system is a big deal. Instead of having one servo per channel, the SBUS system allows for 16 proportional controls and two digital channels for each receiver. Basically, if you’re building an awesome plane with retracts on the landing gear and bomb bay doors, this is what you want to use. [Michael] wanted to use a few SBUS servos for a project he’s working on, so of course he had to reverse engineer this proprietary protocol.

Each SBUS servo operates over a single 100kbps serial connection with a few interesting twists: the signal is transmitted as big endian, but the individual bytes are little endian, something [Michael] figured out after stumbling across this month old mbed post. [Michael] used a serial library written by [fat16lib] and was able to change the parity and stop bits along with a simple hex inverter. Everything worked perfectly when the servo was connected to a an Arduino Mini.

Even though the SBUS system requires special Futaba servos, we can easily see how useful [Michael]’s work would be to outrageously complex robots or cnc machines. Check out the video after the break for a quick demo of [Michael]’s breadboard controlling one of these SBUS servos.

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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.