Hackaday Prize Entry: Powering A Pi From A Battery

Knocking a microcontroller into sleep mode and waking it up on demand or in intervals is common practice in many low power applications, enabling devices to stay in operation for years on a single coin cell battery. Since there are tons of applications where you might want to do similar things with a Raspberry Pi, [Patrick Van Oosterwijck] created the LiFePO4wered/Pi. The module that snaps on to eight GPIO pins of a Pi, extending it by a long life LiFePO4 battery, a charging regulator, and a proper power management. Obviously, it also makes a great UPS.

lifepo_pcbs[Patrick] realized this project by expanding his already available and equally useful LiFePO4wered/USB charging regulator module by a low power MSP430G2131 microcontroller and a load switch. A daemon on the Raspberry Pi speaks to the module over I2C, allowing you to schedule a wake-up timer, let your Pi autoboot after a power outage or just read out the current battery voltage through a command line tool. Once the Pi is safely shut down, the microcontroller will also go to sleep, resulting in a standby current of 8 uA for the whole system. Together with the 500 mAh LiFePo4 cell, that’s theoretically low enough to send your Pi-ncess into a seven-year-long sleep.

LiFePO4wered/Pi is not only good for sleeping, though. [Patrick’s] runtime tests show, that the 500 mAh cell will power a Raspberry Pi Zero and a WiFi dongle for about two hours. Because the Raspberry Pi and many USB peripherals won’t complain when only 3.2 V are present on the VBUS, [Patrick] was able to squeeze out even more runtime by dismissing the boost converter from the design and driving the Pi directly from the battery voltage. If that worries you, you can either read a detailed explanation on why that works so well or just have a look at the more compliant 5 V version.

lifepo_time_laps_cameraEventually, [Patrick] used his module to create a Raspberry Pi time-lapse camera. A little script lets the Pi take a picture on boot up, set a wake-up timer and go back to sleep again. Safely enclosed in a waterproof electric box and deployed into the wild, the camera took 120 pictures on a single charge.

We’re sure the module will find it’s way into many cool projects and we’re counting the hours until we can get one in [Patrick’s] tindie store. Until then, enjoy the time-lapse video:

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Rasberry Pi Zero Plays Every Simpsons Episode Ever at Random

If there’s a better use for Raspberry Pi Zero than a shuffler for episodes of “The Simpsons”, we haven’t heard about it.

Creator [Stephen Coyle] took inspiration from [Will Smith]’s mention of the burning need for such a device on the Tested podcast years back. The gadget is just a Zero with a familiar yellow button – hopefully it’s Pantone 116 C – that randomly selects an episode from the SD card. [Stephen] is clear on his opinion of over half of the program’s oeuvre, having found only seasons 2 through 10 worthy to load on the card. As an aside, we feel pretty old after seeing that all 593 episodes can easily fit on a 128GB SD card – we started out religiously recording every episode on VHS tapes, but had to stop after a few seasons when the collection got too big to handle.

If ripping episodes from DVDs isn’t your style, or you’re still into the first-run stuff, you might want to check out this confusingly named Smart Homer so you never miss an episode.

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Raspberry Pi Balloon Goes Too High, Goes Boom, But Survives

Some people like to get high on a Wednesday afternoon. [Kevin Hubbard] of Black Mesa Labs likes to get really high. Even higher than intended: last month, he flew a helium balloon powered by a Raspberry Pi to 103,000 feet. It was only supposed to go to 90,000, but a fault in the code for the controller meant that it went higher, burst and plunged to the ground. All thanks to an extra hash mark in his code.

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Chess Computers Improve Since 90s

The AlphaGo computer has been in the news recently for beating the top Go player in the world in four out of five games. This evolution in computing is a giant leap from the 90s when computers were still struggling to beat humans at chess. The landscape has indeed changed, as [Folkert] shows us with his chess computer based on a Raspberry Pi 3 and (by his own admission) too many LEDs.

The entire build is housed inside a chess board with real pieces (presumably to aid the human player) and an LED on every square. When the human makes a move, he or she inputs it into the computer via a small touch screen display. After that, the computer makes a move, indicated by lighting up the LEDs on the board and printing the move on the display. The Raspberry Pi is running the embla chess program, which has an Elo strength of about 1600.

While the computer isn’t quite powerful enough to beat Magnus Carlsen, we can only imagine how much better computers will be in the future. After all, this credit-card sized computer is doing what supercomputers did only a few decades ago. With enough Raspberry Pis, you might even be able to beat a grandmaster with your chess computer. Computer power aside, think of the advancements in fabrication technology (and access to it) which would have made this mechanical build a wonder back in the 90s too.

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K.I.S.S. Pi Sprinkler – Just Keep the Plants Alive

A good first step in a project is knowing what you want to do. [Ben Fino] made it clear that his Raspberry Pi Sprinkler control system for his wife’s garden had one goal: keep the plants alive. The resulting project is doing just that and no more.

The circuitry, and plumbing, is straightforward and explained well in the Instructable. All the electronics consists of is the Pi and a MOSFET to take the 3.3v GPIO to 5v to control a relay. The valve controlling the water requires 28v AC which necessitated the relay to control it. There are also three LEDs: one is for power, one to indicate when the valve is opened, and one is an extra for some future purpose.

The intriguing part is the use of weather data from the web to determine if it’s rained recently. Python scripts provided by [Ben’s] friend [Mark Veillette] use a weather site API to get the rainfall data. The main script is set to run once every 24 hours. [Ben] set his system to water unless the previous day had sufficient rain. How much rain and the number of look-back days is programmable.

What a great application of the KISS principle: keep it simple, stupid – except for that third LED without a purpose.

An Open Source Lead Tester

If you’ve ever needed an example of colossal failure of government actors, you need only to look at Flint, Michigan’s water crisis. After the city of Flint changed water supplies from Detroit to the Flint river, city officials failed to add the correct corrosion inhibitors. This meant that lead dissolved into the water, thousands of children were exposed to lead in drinking water, a government coverup ensued, [Erin Brockovich] showed up, the foreman of the Flint water plant was found dead, and the City Hall office containing the water records was broken into.

Perhaps inspired by Flint, [Matthew] is working on an Open Source Lead Tester for his entry into the 2016 Hackaday Prize.

[Matthew]’s lead tester doesn’t test the water directly. Instead, it uses a photodiode and RGB LED to look at the color of a lead test strip. These results are recorded, and with a bit of a software backend, an entire city can be mapped for lead contamination in a few days with just a few of these devices.

One problem [Matthew] has run into is the fact the Pi does not have analog to digital conversion, making reading a photodiode a little harder than just plugging a single part into a pin header and watching an analog value rise and fall. That really shouldn’t be a problem – ADCs are cheap, especially if you only need a single channel of analog input with low resolution. [Matthew] is also looking into using the Pi webcam for measuring the lead test strip. There are a lot of decisions to make, but any functional device that comes out of this project will be very useful in normal, functioning governments. And hopefully in Flint, Michigan too.

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The Dark Arts: Anonymity

Love him or hate him, Edward Snowden knew a thing or two about anonymity. In June of 2013, he blew the whistle on the NSA’s out-of-control programs that can target virtually anyone plugged into the digital age. The former CIA employee was working as a contractor for the NSA, where he had access to highly classified documents for many of these general populace surveillance programs. He eventually took off to Hong Kong and released the documents to a handful of reporters. One of these documents was a power point presentation of the NSA complaining about how the TAILS operating system was a major thorn in their side. Naturally, Snowden insisted that the reporters and himself only communicate via the TAILS O/S. He used PGP, which is an encryption method with the highly sophisticated title of “Pretty Good Privacy”, and asked not to be quoted at length for fear of identification via stylometry.

In this article, we’re going to go over the basics of anonymity, and introduce you to methods of staying anonymous while online.

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