Raspberry Pi

1848 Articles

Hackaday Prize Entry: Raspberry Pi Thermal Imaging

September 25, 2016 by 12 Comments

High up on the list of desirable technologies that are edging into the realm of the affordable for the experimenter is the thermal camera. Once the exclusive preserve of those with huge budgets, over the last few years we’ve seen the emergence of cameras that are more affordable, and most recently a selection of thermal camera modules that are definitely within the experimenter’s range. They may not yet have high resolution, but they are a huge improvement on nothing, and they are starting to appear in projects featured on sites like this one.

One such device is the Melexis MLX90621, a 16×4 pixel thermal sensor array in a TO39 can with an I2C interface. It’s hardly an impulse purchase in single quantities and nor is it necessarily the cheapest module available, but its price is low enough for [Alpha Charlie] to experiment with interfacing it to a Raspberry Pi for adding a thermal camera overlay to the pictures from its visible light camera.

The wiring for the module is simplicity itself, and he’s created a couple of pieces of software for it that are available on his GitHub repository. mlxd is a driver daemon for the module, and mixview.py is a Python graphical overlay script that places the thermal array output over the camera output. A run-through of the device and its results can be seen in the video below the break.

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Want To Wake Up In A Ship’s Warp Core? Circadia Sunrise Clock Makes It So

September 22, 2016 by 24 Comments

Who among you has difficulty rising in the mornings? Sunrise clocks that simulate a — well, sunrise,  are a gentle means of returning to the waking world. [FlorianH], grappling with this very issue, has built his own impressive sunrise clock he has named Circadia. Some sunrise clocks mate an LED with a dev board and call it a day. This work of hardware art will never be confused for something rudimentary.

Standing at 187cm tall, the 8mm thick PCB frame contains three main sections that plug into each other “like Lego”: the top houses a cleverly designed (and virtually silent) propeller clock and a speaker with a 3D-printed, omni-directional reflector. The midsection is reinforced with an MDF column, around which is wrapped 16 strips of 18 RGB LEDs with a heat-molded sheet of acrylic to diffuse the light, while the bottom section has the mid-woofer, the Raspberry Pi 2 brain, most of the electronics, and three switched power supplies.

Built over two years, the primary feature is a variety of themes — with more being added all the time — ranging from rain forest, to arctic, to the warp core of a starship that will rouse you over the course of a half hour. Circadia can also function as a visualizer during a party, or even a Tetris display (a theme that was designed and tested in an afternoon!). Seeing it in action is a treat:

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How To Run A Pagekite Server To Expose Your Raspberry Pi

September 21, 2016 by 9 Comments

Last time I showed you how to expose a web service on a Raspberry Pi (or, actually, any kind of device) by using a reverse proxy from Pagekite. On your Pi, you just need a simple Python script. However, it also depends on the Pagekite server, which isn’t always convenient. There are limits to the free service, and you don’t control the entire thing. The good news is twofold: the same Python script you use to set up the client-side can also set up a server. The other good news is the entire thing is open source.

In practical terms, then, if you have a computer that is always on and has an IP address that can be found on the public internet, you can run your own Pagekite server (they call it a front end) and service your own backends.

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Expose Your Raspberry Pi On Any Network

September 20, 2016 by 42 Comments

Everyone’s talking about the Internet of Things (IoT) these days. If you are a long-time Hackaday reader, I’d imagine you are like me and thinking: “so what?” We’ve been building network-connected embedded systems for years. Back in 2003, I wrote a book called Embedded Internet Design — save your money, it is way out of date now and the hardware it describes is all obsolete. But my point is, the Internet of Things isn’t a child of this decade. Only the name is.

The big news — if you can call it that — is that the network is virtually everywhere. That means you can connect things you never would have before. It also means you get a lot of data you have to find a reason to use. Back in 2003, it wasn’t always easy to get a board on the Internet. The TINI boards I used (later named MxTNI) had an Ethernet port. But your toaster or washing machine probably didn’t have a cable next to it in those days.

Today boards like the Raspberry Pi, the Beagle Bone, and their many imitators make it easy to get a small functioning computer on the network — wired or wireless. And wireless is everywhere. If it isn’t, you can do 3G or 4G. If you are out in the sticks, you can consider satellite. All of these options are cheaper than ever before.

The Problem

There’s still one problem. Sure, the network is everywhere. But that network is decidedly slanted at letting you get to the outside world. Want to read CNN or watch Netflix? Sure. But turning your computer into a server is a little different. Most low-cost network options are asymmetrical. They download faster than they upload. You can’t do much about that except throw more money at your network provider. But also, most inexpensive options expose one IP address to the world and then do Network Address Translation (NAT) to distribute service to local devices like PCs, phones, and tablets. What’s worse is, you share that public address with others, so your IP address is subject to change on a whim.

What do you do if you want to put a Raspberry Pi, for example, on a network and expose it? If you control the whole network, it isn’t that hard. You usually use some kind of dynamic DNS service that lets the Pi (or any computer) tell a well-known server its current IP address (see figure below).

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The Cicada: A Parasite Art Piece With Commitment Issues

September 19, 2016 by 18 Comments

How often do you think deeply about the products around you? How about those you owned five years ago? Ten? The Cicada — brainchild of [Daniel Kerris] — is an art piece that aims to have the observer reflect on consumer culture, buyer’s remorse, and wanting what we cannot have.

The Cicada consists of an ultrasonic sensor feeding data to a Raspberry pi which — calculating the distance of an approaching human — either speeds up or slows down a servo motor connected to a General Electric Walkman’s cassette speed potentiometer. Upon detecting someone approaching, The Cicada begins to loop the chorus of Celine Dion’s “I Will Always Love You”. As you move closer, the tape speed slows, and there is a transition from love at first sight to nightmarish drawl as the music slows.

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Hackaday Prize Entry: Text To Speech The Hard Way

September 18, 2016 by 10 Comments

Studies have shown reading to children leads to improved academic performance later in life, a trait that will make them more competitive in the workforce, and ultimately happier human beings. It follows, then, that having a robot read to children will also lead to happier and more productive adults, while normalizing the cyborg uprising takeover of the AI apocalypse of 2037.

It’s a good thing the above paragraph is a complete non-sequitur and has nothing to do with this Hackaday Prize entry. The TextEye, [Markus]’ entry for the Assistive Technology portion of the Hackaday Prize, is a handheld device that translates the written word into speech, useful for anyone who either can’t see well or can’t read gooder. Yes, it will also read to children, but so did Teddy Ruxpin.

If you’re keeping track, this isn’t the first time [Markus] has entered this project in a Hackaday Prize contest. The first time was six months ago in the Hackaday / Adafruit Raspberry Pi Zero contest. [Markus] was inspired by a group of blind computer science students using specialized hardware that allowed them to study the same thing as everyone else.

Since the first few project logs, a lot has changed in this project. You can buy a Pi Zero easily, and the updated Pi Zero 1.3 now comes with a camera connector. [Markus] is swapping out his Pi Model A and USB webcam for the Pi Zero and Pi camera. The software remains the same — GraphicsMagick, Tesseract OCR, Festival and Wiring Pi handle reading text and turning those words into speech — with a slight refactoring of the code. It’s a great use for the Pi Zero, and an excellent example of an Assistive Technology, and we’re happy to see it again in the Hackaday Prize.

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Clustering A Lot Of Raspberry Pi Zeros

September 18, 2016 by 57 Comments

It became something of a cliché a few years ago in online discussions, whenever a new single board computer was mentioned someone would pop up and say something like “Imagine a Beowulf cluster…“. Back then it was said largely in jest, but with the current generation of boards it’s a distinct possibility. Who hasn’t looked at a Raspberry Pi and idly thought about a cluster of them, or even created one!

[Electronoob] did just that, creating a variety of Raspberry Pi cluster configurations, the most impressive of which is a stack of 32 Pi Zeros mounted together with stand-offs. The plan was to network it via USB, for which he initially considered building a backplane, but was put off by the cost of vertical USB connectors and instead went for a wired approach. If there is a lesson to be learned from his experiences it is that buying very cheap USB cables is a minefield: his pile of eBay specials turned out to have significant numbers of faults. He’s now faced with a stark choice, solder  32 sets of USB pads on the base of each Zero or buy better cables.

The stack of Zeros is pretty impressive, but so what, you think. It’s still not working properly. But the Zero cluster isn’t his only work. He’s also created a set of very nicely executed Ethernet clusters using the larger Pi boards, and the way he’s mounted them on top of compact Ethernet switches sets them apart from some of the more spaghetti-like Pi clusters.

It’s true a Pi cluster won’t cut it in the world of supercomputers, you could almost certainly buy more bang for your buck without too much effort. But it does represent a very accessible way to learn about cluster computing, and you have to admit it a stack of Zeros does look rather impressive.

We’ve seen quite a few Pi clusters here since 2012, the biggest of which is probably this 120 node behemoth, complete with screens.