Want a low-cost ARM platform? Grab a Prepaid Android Phone!

What would you pay for a 1.2Ghz dual-core ARM computer with 1GB RAM, 4GB onboard flash, 800×600 display, and 5 megapixel camera? Did we mention it also has WiFi, Bluetooth, and is a low power design, including a lithium battery which will run it for hours? Does $15 sound low enough? That’s what you can pay these days for an Android cell phone. The relentless march of economies of scale has finally given us cheap phones with great specs. These are prepaid “burner” phones, sold by carriers as a loss leader. Costs are recouped in the cellular plan, but that only happens if the buyer activates said plan. Unlike regular cell phones, you aren’t bound by a contract to activate the phone. That means you get all those features for $15-$20, depending on where you buy it.

android-logo-transparent-backgroundThe specs I’m quoting come from the LG Optimus Exceed 2, which is currently available from Amazon in the USA for $20. The same package has been available for as little as $10 from retail stores in recent weeks. The Exceed 2 is just one of several low-cost Android prepaid phones on the market now, and undoubtedly the list will change. How to keep up with the current deals? We found an unlikely place. Perk farmers. Perk is one of those “We pay you to watch advertisements” companies. We’re sure some people actually watch the ads, but most set up “farms” of drone phones which churn through the videos. The drones earn the farmer points which can be converted to cash. How does this all help us? In order to handle streaming video, Perk farmers want the most powerful phones they can get for the lowest investment. Subreddits like /r/perktv have weekly “best deals” posts covering prepaid phones. There are also tutorials on rooting and debloating current popular phones like the Whirl 2 and the Exceed 2.

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A simple project to get you started with the Android ADK


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.

Arduino lawn care is web-controlled

[Joe Fernandez] is fairly new to the hardware side of the hobby, but he seems to have easily found his way on this project. He wanted to build his own web-bridge for his Toro lawn sprinkler system. He pulled it off with style and shows off the spoils of his work in the clip after the break.

He started with an Android ADK, crafting some web magic to use a REST interface and JSON packets as a communications scheme. This makes it possible to control the system from anywhere as long as you have an Internet connection. The rest of the hardware evolved as his needs became clear. The first hunk was to add an Ethernet shield so that he didn’t need to have his Android phone connected to the system for it to work. From there he needed to control the solenoid valves on the system and grabbed three relay shields from Seeed Studios for this purpose.

As you can see, all of that hardware has a home on a polyethylene cutting board. The terminal blocks at the bottom keep the connections nice and neat as they interface with the sprinkler system. We were happy to hear that the stock controller still works, this add-on doesn’t permanently alter it in any way. That’s going to be important if he ever wants to sell the home.

Still using a traditional sprinkler instead of an in-ground system? Perhaps this variable range hack is for you.

Android phone serves as Arduino terminal

Looking to use his Arduino when on-the-go, [Oleg] has been working on a way to use the Android ADK terminal emulator with the Arduino. The Android side uses ADK features along with a custom application. [Oleg] received help from his friend [Victor] when developing the program for Android (you can check out our own Android Development tutorials if you’re interested in learning how this is done). The .apk file is available for download, but they’re waiting to release the source code until they can clean it up and get some of the gnarly bugs out of the beta version.

A USB host shield for the Arduino is needed to connect to an Android hand set. You’ll be able to send and receive strings via the terminal, with support for carriage return and life feed characters. Unfortunately this doesn’t allow you to change, compile, or write sketches to the Arduino. But it might come in very handy when trouble shooting a project when a computer is not around, or just for using an Android phone as an output.

Google ADK on an EvalBot


After learning that Google’s ADK relied on using an Arduino-compatible board, [Benjamin] was disappointed that other microcontroller platforms weren’t invited to the party. Rather than switch camps, he took it upon himself to get the ADK working with his EvalBot. In fact, his modifications should allow the ADK to work with nearly any Stellaris ARM kit.

The hack is composed of two parts. The first, and most important bit is the USB host driver he developed to work with the ADK. The code borrows some bits from Texas Instruments, and will be published on GitHub once he gets a chance to clean up the source a bit. To get his phone working with the EvalBot, he also had tweak the external USB power supply in order to provide the current required to operate properly with other USB-connected hardware.

It’s always nice to have more options when working with Google’s ADK, and [Benjamin’s] work is likely a welcome addition to any Stellaris developers toolkit.

Continue reading to see a quick video of his EvalBot ADK demo.

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Google ADK clones pack a few extra features, hopefully far cheaper than the original


[charliex] from Null Space Labs wrote in to share a project that he and the rest of the gang have been working on over the last few weeks. The team has been remixing and building clones of the Google ADK demo board we saw earlier this year, in hopes of getting a huge batch prepped before Defcon 19.

Their version makes subtle changes to the original, such as extra header rows for Mega AVRs, higher quality RGB LEDs, and a nifty pirate-Android logo. They also added the ability for the board to send and receive IR signals allowing it to be used as a TV-B-Gone, as well as in more fruitful pursuits. The Arduino board used with the ADK has only undergone minor revisions, most of which were layout related.

[charliex] hasn’t mentioned a price for their improved ADK boards, but we’re guessing they will be substantially cheaper than the official Google version. In the meantime, check out their site for a boatload of pictures and videos of these boards undergoing various stages of construction.

IOIO upgrades get a bit easier

The IOIO, a breakout board for Android phones that predates the Android Developer Kit hardware, is a now a little bit easier to upgrade. That’s because [Ytai’s] IOIO manager app just his the Android market. The PIC24F that sits proudly on top of the board has always been running a bootloader, but for security reasons it is programmed to only talk to apps that have been officially signed. Now that there’s an app that meets this qualification, you can upgrade the firmware from your phone without the need for an external programmer.

What about the bootloader itself? Surely that will need upgrades over time, right? Well, yes. [Ytai’s] announcement today also came with an option for upgrading the bootloader but with one caveat. You’ll need two IOIO boards to complete the upgrade. One connects to the phone and becomes a programmer, while the other lays back and waits for a refreshing code flash.