Can An 8 Node Raspberry Pi Cluster Web Server Survive Hackaday?

November 5, 2013 by Adam Fabio 50 Comments

Plenty of folks have used their Raspberry Pi as a web server. [Steve] however is the first 8 node load balanced pi cluster server we’ve run into. While we have seen pi clusters before, they’ve never been pressed into service as a public facing web server. [Steve] has created a really nice informative website about the Raspberry Pi, and Linux in general. As his page views have increased, he’s had to add nodes to the server. Currently [Steve] sees about 45,000 page views per month.

At first glance it would seem that the load balance system would be the weak link in the chain. However, [Steve] did realize that he needed more than an Pi to handle this task. He built the load balancer using an old PC with 512MB of RAM and a 2.7GHz x86 CPU. The most important thing about the balancer is dual network interfaces, one side facing the internet, the other facing the Pi cluster. The balancer isn’t a router though. Only HTTP requests are forwarded. The Pi nodes themselves live on their own sub net. Steve has run some basic testing with siege, however nothing beats a real world test. We figured a couple of links in from Hackaday would be enough to acid test the system.

VT100 Gets BeagleBoned

October 16, 2013 by Adam Fabio 19 Comments

vt100

How do you make a great terminal even better? The answer is simple: add a BeagleBone Black to it! [Brendan] got his hands on one of the staples of classic computing, the DEC VT100 terminal. The VT100 was produced from 1978 to 1983. The terminal was so widely used that it became the standard for other terminals to emulate. Open any terminal program today and chances are you’ll find a setting for VT100 emulation.

[Brendan] originally hooked his terminal up to a laptop running Linux. The terminal, cables, and the laptop itself became quite a bit to manage on a small desk. To combat this he decided to add a BeagleBone Black inside the terminal case. It turns out the VT100 actually lends itself to this with its Standard Terminal Port (STP) connector. The STP was designed to add a “paddle board” in-line with the serial stream of the terminal. DEC and third party manufacturers used this port to add everything from disk drives to entire CPM computers to the VT100.

[Brendan] began by designing a board to interface between the VT100 and the BeagleBone. The board level shifts serial lines from the BeagleBone to the VT100. The STP also allows the terminal to provide power to the BeagleBone Black. He did notice some power glitches as the supply of the VT100 came up. This was solved with a standard TI TL77xx voltage supervisor chip. The hardest part of the entire design was the card edge connector for the STP. [Brendan] nailed the dimensions on the first try. In the end [Brendan] was rewarded with a very clean installation that didn’t require any modification to a classic piece of hardware.

We should note that most PCB houses use Electroless Nickel Immersion Gold (ENIG) as their standard coating. This will work for a card edge connector that will be plugged in and removed a few times. Cards that will be inserted and removed often (such as classic console cartridges) will quickly scrape the ENIG coating off. Electroplated Gold over Nickel is the classically accepted material for card edge connectors, however the process most likely is not going to come cheap in hobbyist quantities.

A Motherboard For A WiFi Enabled SD Card

October 9, 2013 by Brian Benchoff 14 Comments

Over the last few months, a few very capable hackers have had a hand in cracking open a Transcend WiFi-enable SD card that just happens to be running a small Linux system inside. The possibilities for a wireless Linux device you can lose in your pocket are immense, but so far no one has gotten any IO enabled on this neat piece of hardware. [CNLohr] just did us all a favor with his motherboard for these Transcend WiFi SD cards, allowing the small Linux systems to communicate with I2C devices.

This build is based upon [Dmitry]’s custom kernel for the Transcend WiFiSD card. [CNLohr] did some poking around with this system and found he could use an AVR to speak to the card in its custom 4-bit protocol.

The ‘motherboard’ consists of some sort of ATMega, an AVR programming header, a power supply, and a breakout for the I2C bus. [Lohr] wired up a LED array to the I2C bus and used it to display some configuration settings for the WiFi card before connecting to the card over WiFi and issuing commands directly to the Linux system on the card. The end result was, obviously, a bunch of blinking LEDs.

While this is by far the most complex and overwrought way to blink a LED we’ve ever seen, this is a great proof of concept that makes the Transcend cards extremely interesting for a variety of hardware projects. If you want your own Transcend motherboard, [CNLohr] put all the files up for anyone who wants to etch their own board.

Advanced Transcend WiFi SD Hacking: Custom Kernels, X, And Firefox

September 19, 2013 by Adam Fabio 95 Comments

[Dmitry] read about hacking the Transcend WiFi cards, and decided to give it a try himself. We already covered [Pablo’s] work with the Transcend card. [Dmitry] took a different enough approach to warrant a second look.

Rather than work from the web interface and user scripts down, [Dmitry] decided to start from Transcend’s GPL package and work his way up. Unfortunately, he found that the package was woefully incomplete – putting the card firmly into the “violates GPL” category. Undaunted, [Dmitry] fired off some emails to the support staff and soldiered on.

It turns out the card uses u-boot to expand the kernel and basic file system into a ramdisk. Unfortunately the size is limited to 3MB. The limit is hard-coded into u-boot, the sources of which transcend didn’t include in the GPL package.

[Dmitry] was able to create his own binary image within the 3MB limit and load it on the card. He discovered a few very interesting (and scary) things. The flash file system must be formatted FAT32, or the controller will become very upset. The 16 (or 32)GB of flash is also mounted read/write to TWO operating systems. Linux on the SD card, and whatever host system the card happens to be plugged in to. This is dangerous to say the least. Any write to the flash could cause a collision leading to lost data – or even a completely corrupt file system. Continue reading “Advanced Transcend WiFi SD Hacking: Custom Kernels, X, And Firefox” →

Monitoring A Sick Bird Using The Raspberry Pi

July 25, 2013 by Mike Szczys 6 Comments

sick-bird-monitoring-with-rpi

[Jorge Rancé] was nursing a sick bird back to health. He found it on the street with a broken leg, which required a mini plaster cast for it to heal correctly. But felt bad when leaving the house for long periods. He grabbed some simple hardware and put his mind at easy by building an Internet connected bird monitoring system. It’s really just an excuse to play around with his Raspberry Pi, but who can blame him?

A webcam adds video monitoring using the Linux software called “motion” to stream the video. This is the same package we use with our cats when we travel; it provides a continuous live stream but can also save recordings whenever motion is detected. He added a USB temperature sensor and attached a water level sensor to the GPIO header. These are automatically harvested — along with a still image from the webcam — and tweeted once per hour using a bash script. He just needs to work out automatic food and water dispensing and he never needs to return home! Bird seed shouldn’t be any harder to dish out than fish food, right?

Turning The Samsung Galaxy Note 10.1 Into A Proper Linux Box

March 5, 2013 by Brian Benchoff 23 Comments

Over on the xda developers forum, [exception13] shows us the work he’s put into geting Debian running on his Samsung Galaxy Note 10.1, allowing him to dual boot Android and Linux on a single device.

The project is still in a fairly early state, but so far [exception13] has most of the goodies required for a decent Linux experience running already. There’s WiFi, bluetooth, sound, usb-otg and touchscreen support, as well as support for the Note’s S Pen, the Wacom digitizer that basically turns the Galaxy Note 10.1 into an Intuos touch pad.

There’s still a lot of work work to be done, including getting the camera up and running, as well as enabling the GPS receiver. Still, it’s a very cool project that puts the power of a proper desktop interface into a tablet with enough horsepower to get something useful done.

If you’d like to get this running on your Galaxy Note, [exception13] has a download avaiable over on Google Code. There’s also a video [exception13] put together demoing all the cool stuff his Note can do, you can check that out after the break.

Continue reading “Turning The Samsung Galaxy Note 10.1 Into A Proper Linux Box” →

Ubuntu With A GUI On A Beagleboard

February 25, 2013 by Brian Benchoff 16 Comments

beagle

The Raspberry Pi is great if you’re looking for a cheap yet powerful computer running Linux, but let’s not forget all the other ARM dev boards out there. [Adam] spent some time this weekend putting together an Ubuntu distro for his Beagleboard XM to give it the convenience of a GUI and a whole bunch of drivers to get a lot of stuff done.

The Beagleboard XM is another high power ARM dev board that is a little more capable than the Raspberry Pi. With an integrated USB hub, LVDS LCD displays, and a camera board, the Beagleboard already has a lot of peripherals that are now only promised for the Raspberry Pi. The only problem with the Beagleboard XM is the state of drivers and software; a problem [Adam] resolved by bringing Ubuntu to the Beagleboard.

[Adam]’s distro comes with all the goodies a relatively high-powered ARM dev board should have: Python, scipy, numpy, and a few cool extras such as GIMP and Chromium. He says it’s a bit faster than the stock Raspbian distro on the Raspberry Pi, so if you’re looking for the best ARM/Linux dev board for your next project, you may want to give [Adam]’s distro a try.