Want A Low-cost ARM Platform? Grab A Prepaid Android Phone!

September 10, 2015 by Adam Fabio 113 Comments

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.

The 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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Simple USB Power Meter

September 7, 2015 by Anool Mahidharia 24 Comments

The USB interface is being increasingly used as a power supply and charging port for all kinds of devices, besides data transfer. A meter to measure the electrical parameters of devices connected to a USB socket or charger would be handy on any hacker workbench. The folks at [electro-labs] designed this simple USB power meter which does just that.

The device measures voltage and current and displays them, along with the calculated power, on the small 0.5″ OLED display. The circuit is built around an ATmega328. To keep the board size small, and reduce component count, the microcontroller is run off its internal 8MHz clock. A low-resistance shunt provides current sensing which is amplified by the LT6106 a high side current sense amplifier before being fed to the 10 bit analog port of the ATmega. A MCP1525 precision voltage reference provides 2.5V to the Analog reference pin of the microcontroller, resulting in a 2.44mV resolution. Voltage measurement is via a resistive divider that has a range of up to 6V. An Arduino sketch reads voltage and current data on the analog ports and displays measurements on the display. The measured data is averaged to filter out noise.

The OLED display has a SPI interface and requires the u8glib library. The project uses all SMD parts, but is fairly easy to assemble by hand and could be a nice starter project if you want to wet your feet on surface mount assembly techniques. It’s designed using SolaPCB EDA software, and the source files for schematic and board layout are available as a ZIP archive. Download the BoM and Arduino code and you have everything needed to build this nifty device.

Thanks to [Abdulgafur] for sending in this tip. And if you are looking for a more comprehensive solution, check the awesome Friedcircuits USB Tester which we reviewed earlier and is available in the Hackaday Store.

Transformers, Birthday Cakes In Disguise

September 1, 2015 by Richard Baguley 5 Comments

[Russel Munro] decided to go all-out for his son’s birthday cake: he made a Transformers robot cake that, well, transforms from a truck into a robot, Optimus Prime style. His impressive build has the actions of the original: first, the front rears up to lift the head, then the back lifts to form the body and the head and arms pop out of the top. Underneath the thin fondant exterior is a 3D printed body, driven by a mechanism in the base. He used fishing line to lift the parts, which is pulled by a motor salvaged from a CD player, being driven by an EasyDriver board from Sparkfun.

The main issue he had to overcome was weight: apparently he underestimated the weight of the fondant that covers the cake, and had to do some last-minute work to strengthen the drive mechanism, and skip plans for the more ornately decorated version that his wife had planned. But the look of glee on his son’s face when he operates it at the party is the best bit. In these days of CGI and computer games, it is good to remind the kids that there is still a lot of fun to be found in ingenuity and liberal quantities of hot glue.

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Arduino Video Over 2 Wires For Under $50: Mesa-Video

September 1, 2015 by Richard Baguley 60 Comments

If you want video support on your project, you might start from a device like a Raspberry Pi that comes with it built in. [Kevinhub88] doesn’t accept such compromises, so he and his Black Mesa Labs have come up with a whole new way to add video support to devices like the Arduino and other cheap controllers. This project is called Mesa-Video, and it can add digital video at a resolution of up to 800 by 600 pixels to any device that has a single serial output.

The video is created by an FT813, a low cost GPU from FTDI that offers a surprising amount of video oomph from a cheap, low power chip ~~(he has demoed it running from a lemon battery)~~, meaning that he is hoping to be able to sell the Mesa-Video for under $50.

UPDATE: [KevinHub88] let us know that he didn’t actually power the device from a lemon battery, as you would need a lot of lemons to make 50mA at 5V. Apologies for any confusion!

However, Mesa-Video is just the beginning. [Kevinhub88] wanted to get around the problem of stacking shields on Arduinos: add more than one and you get problems. He wanted to create an interface that would be simpler, faster and more open, so he created the Mesa-Bus. This effectively wraps SPI and I2C traffic together over a simple, fast serial connection that doesn’t require much decoding. This means that you can send power and bi-directional data over a handful of wires, and still connect multiple devices at once, swapping them out as required. You could, for instance, do your development work on a PC talking to the prototype devices over Mesa-Bus, them swap the PC out for an Arduino when you have got the first version working in your dev environment. Is the Arduino not cutting it? Because Mesa-Bus is cross-platform and open source, it is easy to swap the Arduino for a Raspberry Pi without having to change your other devices. And, because all the data is going over a simple serial connection in plain text, it is easy to debug.

It’s an ambitious project, and [Kevinhub88] has a way to go: he is currently working on getting his first prototype Mesa-Bus devices up and running, and finalizing the design of the Mesa-Video. But it is an impressive start and we’ll be keeping a close eye on this work. Hopefully he can avoid that head crab problem as well because those things are as itchy as hell.

Before Arduino There Was Basic Stamp: A Classic Teardown

August 27, 2015 by Brian Benchoff 121 Comments

Microcontrollers existed before the Arduino, and a device that anyone could program and blink an LED existed before the first Maker Faire. This might come as a surprise to some, but for others PICs and 68HC11s will remain as the first popular microcontrollers, found in everything from toys to microwave ovens.

Arduino can’t even claim its prominence as the first user-friendly microcontroller development board. This title goes to the humble Basic Stamp, a four-component board that was introduced in the early 1990s. I recently managed to get my hands on an original Basic Stamp kit. This is the teardown and introduction to the first user friendly microcontroller development boards. Consider it a walk down memory lane, showing us how far the hobbyist electronics market has come in the past twenty year, and also an insight in how far we have left to go.

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We Have A Problem: Earthquake Prediction

August 26, 2015 by Will Sweatman 71 Comments

Nepal | 25 April 2015 | 11:56 NST

It was a typical day for the 27 million residents of Nepal – a small south Asian country nestled between China and India. Men and women went about their usual routine as they would any other day. Children ran about happily on school playgrounds while their parents earned a living in one of the country’s many industries. None of them could foresee the incredible destruction that would soon strike with no warning. The 7.8 magnitude earthquake shook the country at its core. 9,000 people died that day. How many didn’t have to?

History is riddled with earthquakes and their staggering death tolls. Because many are killed by collapsing infrastructure, even a 60 second warning could save many thousands of lives. Why can’t we do this? Or a better question – why aren’t we doing this? Meet [Micheal Doody], a Reproductive Endocrinologist with a doctorate in physical biochemistry. While he doesn’t exactly have the background needed to pioneer a novel approach to predict earthquakes, he’s off to a good start.

He uses piezoelectric pressure sensors at the heart of the device, but they’re far from the most interesting parts. Three steel balls, each weighing four pounds, are suspended from a central vertical post. Magnets are used to balance the balls 120 degrees apart from each other. They exert a lateral force on the piezo sensors, allowing for any movement of the vertical post to be detected. An Arduino and some amplifiers are used to look at the piezo sensors.

The system is not meant to measure actual vibration data. Instead it looks at the noise floor and uses statistical analysis to see any changes in the background noise. Network several of these sensors along a fault line, and you have yourself a low cost system that could see an earthquake coming, potentially saving thousands of lives.

[Michael] has a TON of data on his project page. Though he’s obviously very skilled, he is not an EE or software guy. He could use some help with the signal analysis and other parts. If you would like to lend a hand and help make this world a better place, please get in touch with him.

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Build A Sensor Network Around A Weather Station

August 24, 2015 by Richard Baguley 4 Comments

[Yveaux] had a problem. The transmitter on his outdoor weather station had broken, rendering the inside display useless. He didn’t want to buy a new one, so, like the freelance embedded software designer that he is, he decided to reverse engineer the protocol that the transmitter uses and build his own. He didn’t just replace the transmitter module, though, he decided to create an entire system that integrated the weather system into a sensor network controlled by a Raspberry Pi. That’s a far more substantial project, but it gave him the ability to customize the display and add more features, such as synching the timer in the display with a network clock and storing the data in an online database.

Fortunately for [Yveaux], the transmitter itself was fairly easy to replace. The weather station he had, like most, transmitted on the 868MHz frequency, which is a license-free ISM (Industrial, Scientific and Monitoring) spot on the spectrum. After some poking around, he was able to figure out the protocol and teach the Pi to speak it. He then added a Moteino and an nRF2401+ transmitter to the weather station, so it can send data to the Pi, which then sends it to the display. It is a more complicated setup, but it is also much more flexible. He’s had it running for a couple of years now and has collected more than a million sensor readings.