Category Archives: hardhack

The Raspberry Pi

Unless you’ve been living under a rock for the last six months or so, you’ll almost certainly have heard of the Raspberry Pi. If not, here’s the low-down. The Raspberry Pi is a single-board computer aimed at the hobbyist and educational markets. It comes in two flavours, the Model A and Model B, which are subtle references to the BBC Micro computers of the 1980s and 90s. Unfortunately, for the foreseeable future only the Model B – the higher specification model – is scheduled for production. Lurking within the guts of this credit-card sized wonder is 256mb of RAM, and a 700MHz ARM chip that is easily capable of being pushed to 800MHz. For audio and video there are RCA video and 3.5mm audio out, as well as an HDMI port. Resolutions covered range from VGA all the way up to 1080p (and beyond!), with almost all PAL and NTSC video standards covered. Connectivity is a doddle, as a 10/100 Ethernet socket is included on the board. WiFi is also possible; although ARM devices are notoriously finicky about which USB adapters they will work with. I/O is covered too – two USB ports are provided, and are extensible with a hub, and GPIO (general-purpose input/output) pins are provided for connections in and out to various devices, more about which will be covered shortly.

Raspberry Pi Board

The Raspberry Pi viewed side-on. Visible here is the the HDMI port (front centre), the SD card slot (left) the GPIO pins (back left), RCA video (yellow jack) USB ports (back right) and Ethernet port (front right).

While unfortunately the hardware of the Raspberry Pi is almost unchangeable (short of the size of the SD card used), this is more than made up by the choice of operating systems. In true hacking fashion, several operating systems have sprung up, each doing different things. Here are a selection:

1) Raspbian “Wheezy”

Raspbian is based on the Debian kernel, and is the recommended start point for beginners to the Raspberry Pi. It boots to a command prompt by default, but pre-installed is LXDE – a lightweight X11 manager. Other tools included include the Midori web browser, and all the development tools you’d expect on a Linux system, including Python and Java compilers. Of course, since it’s a Debian installation, new software is a doddle to install using the package manager. Within minutes I had set up VLC and was playing 1080p video with no problems.

2) Arch Linux ARM

Arch Linux is extremely popular with the modders and tweakers of the Raspberry Pi community. Its no-frills approach centres on “simplicity and full control for the end-user”. By default, no X11 server is included – it is up to the user to decide which (if any) they would like. Obviously, this distribution is not recommended for those with little to no Linux knowledge.

3) RaspBMC

On the other end of the scale, RaspBMC is totally different to either of the distributions mentioned above. When you use this distribution to boot the Raspberry Pi, it becomes a fully-fledged home media centre, with the ability to play films, music and even YouTube videos. RaspBMC is based on the very popular XBMC, a cross-platform media centre that is used by countless people worldwide.


RaspBMC screenshot

The default home screen for the really quite good RaspBMC media centre operating system for the Raspberry Pi.

One of the main reasons that the Raspberry Pi came about was to teach children in schools about electronics and programming. As such the GPIO pins can be used to interact with code and give sensor readings to programs. Unfortunately, in Raspbian at least, the Python modules for interacting with the GPIO pins are not included by default. Instructions for installing them are given here.  A popular way to interface the Raspberry Pi is a simple ribbon cable and a prototyping board, which will let you try out many different combinations before settling on something more permanent. One of the peripherals that has generated the most buzz lately is a camera module featured here which would pave the way to features such as image recognition for navigation, or more multimedia capabilities.

As with most things, however, there are a few drawbacks, but what else did you expect from a machine costing £25/$35? The biggest caveat for me was initially the lack of hardware MPEG-2 decoding, which meant my whole library of movies would have to be transcoded to h.264 for smooth playback on the device. However, the Raspberry Pi Foundation has now released licenses for roughly £2.50 for MPEG-2 and £1.50 for VC-1. The other gripe that some may have is the lack of expandable RAM, as it is all contained within the CPU. Such users may find the VIA APC or cubieboard a little more suitable for their use, however, for pure value for money and form factor, the Raspberry Pi is hard to beat.

Edit (1/11/12) – As of October 15th, the Raspberry Pi now ships with 512MB RAM, making it an even more attractive proposition for its price point.

Two cities, two hack days

During March and May, I attended two very different hack days. The first was part of Bath’s first ever digital festival, aptly called, Bath Digital Festival. The hack day was organised by local web development consultancy Storm.

Unlike previous Storm hack days that have had a theme, this one was open ended for the developers to develop anything they wished. They have had good success in their previous hack days resulting in some of the hacks being turned into finished products and released on Apple’s App Store, such as Spyhunt and Shaken created by local software development company Riot.

At the hack day I teamed up with fellow Ruby developer and hardware hacker Paul Leader (who just happens to work at Storm). We had borrowed a receipt printer from Mike Ellis (organiser of Bath Digital Festival) with the intention of plumbing it up to the internet in order to print out tweets from the conference as a physical takeaway memento for festival goers.

Arduino Printer wiring diagram

Working from a highly complicated wiring diagram, we attempted to connect the printer to the internet. Unfortunately for us after many hours in the morning trying to get this to work, we eventually gave up and had lunch. One of my fellow attendees sums this up quite nicely on her blog.


“I also spent a large part of the day sat next to Paul and Julian who were attempting to turn an old receipt printer into a tweet printer – sadly, they couldn’t get it to work, which was a shame – but it was interesting to see the processes and patience they both possessed to get to the desired result (or at least close to it).”

As is the way with most events the wifi during the morning wasn’t quite up to par, so the other 60+ developers in the room found it hard to implement the ideas they wanted to build. After a lunch the wifi was going strong and people started hacking again, I mainly spent the afternoon, finding out what others were working on, and also worked on a twitter text analysis tool with another at attendee.

I think the day went really well, I spoke to some interesting people and thought the event was well organised.

MRD Hack day

The Managing Research Data hack day in Manchester was part of the JISC call by the same name being run by Simon Hodson. Although technically I am not part of any of the projects in the MRD call, I was still asked to attend. The hack day was actually a hack two days, with the room we were in open until the last person left.

After a morning of talks about various projects on the MRD call and various other data related presentations, it was time to start/join a team and brainstorm some ideas. I joined forces with Nick Jackson and Harry Newton of Lincoln University and Nick Syrotiuk of Mimas. The idea of our project came from Joss Winn which he had got from an academic at Lincoln. The basic idea was to create a system whereby an academic could see the outputs of all the research projects not just in their department, but across theirs and every other university.

To get started we first chose a project name from a random name generator, and then I created a GitHub project for it. The project would now and forever be know as Project Rainbow Beam. Built onto of MongoDB I created a simple Sinatra web app to accept a JSON payload which would then be added to the Mongo database. We soon realised that the incoming JSON data need to by sanitised, I volunteered. As I was now chief of sanitisation, Nick J, rewrote the front end using a PHP framework called Codeigniter. To keep enable optimum developer communication we created a chatroom on Campfire, as we were using Campfire, it seemed a good idea to hook GitHub to the chat room, so that every time we pushed code, Campfire would play a Vuvuzela on all of our computers.

Skip to many hours later, Nick J and I were the last to go to bed having been up many hours hacking away at the project.

By mid to late morning day two, we had a fully Bootstrapped website, documentation, api endpoint, data sanitizer, and live feed which was updated via Pusher.

At the hack event, it was decided to vote on all the hack projects that had been going on to see which one would win a further two days development work. With the developers being whisked away to a hotel and given two days to make their project better. Unfortunately we didn’t win this, although our project was well received. The prize of getting two more days to work on their project went to the BitTorrent group whose idea was to use BitTorrent and SWORD to move large research data sets around.


These two events were very different, and were targeting very different audiences. However the common thread they shared was they were meant for developers. They both did well in catering for developer needs, coffee, wifi, and electricity. It was great to be part of these two events, I learned a lot and met lots of great people. I look forward to the next hack day to find a new challenge to work on.

USB webcam fun

Bought a pair of webcams (mostly for the purposes of playing with opencv). When plugged in, the uvcvideo kernel module recognises them, and they self-report to the lsusb command as 18ec:3288. However, by default they fail to work (ioctl error).

v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
v4l2: ioctl set format failed: Invalid argument
tv.c: norm_from_string(pal): Bogus norm parameter, setting default.
v4l2: ioctl enum norm failed: Invalid argument
Error: Cannot set norm!
Selected input hasn't got a tuner!
v4l2: ioctl set mute failed: Invalid argument

As is so often true there is an answer for this problem at the linux UVC dev list. Reproducing for the record the wise words of Laurent Pinchard,

Try setting the quirks parameter to 2 before plugging your webcam (either with ‘modprobe uvcvideo quirks=2‘ if the driver is not already loaded, or with ‘echo 2 > /sys/modules/uvcvideo/parameters/quirks‘ if the driver is already loaded).

To make these settings permanent,you need to create the file /etc/modprobe.d/uvcvideo.conf containing the line:

options uvcvideo quirks=2

From then on, the uvcvideo module will always be loaded with the “quirks=2” option and dmesg will show this line when loading the module:

uvcvideo: Forcing device quirks 0x2 by module parameter for testing purpose.
uvcvideo: Please report required quirks to the linux-uvc-devel mailing list.

Linux on a Toshiba NB200

Thanks to Ultim8Fury, Leesa and Nick255 for the following.

Presumably as it’s a fairly new model, after setting up linux (Ubuntu Netbook Remix in this case) on a Toshiba NB200 I ran into a few little problems.  Most of the smaller ones were solved/mitigated by Ultim8Fury’s excellent Setup Guide here.  However if, like me, you had windows off and linux on faster than ** then you may have run into the ‘enabling wifi’ problem.

The drivers suggested by Ultim8Fury cannot turn the card on and windows XP will not reinstall without some very advanced ‘slipstreaming’ technique due to a lack of drivers for the RAID interface.  So if you forgot to enable wireless before removing XP and do not own a copy of Vista (presumably this may work, I don’t actually know) how do you enable the card?

It was Leesa’s explaination of how to enable bluetooth and Nick255’s adaptation of it that provided the answer.

Originally Posted by Leesa
Bluetooth is working with omnibook module:

  1. Get sources from…1217-1_all.deb
  2. Make sure Bluetooth is enabled in Windows
  3. sudo apt-get install module-assistant build-essential
  4. sudo m-a a-i omnibook-source
  5. Try it: sudo modprobe omnibook ectype=14
  6. Make it autoload:
  • sudo nano /etc/modules
  • Put “omnibook” at the latest line
  • sudo nano /etc/modprobe.d/omnibook.conf:

options omnibook ectype=14 userset=0 lcd=0 display=0 blank=0 battery=0 ac=0 bluetooth=1

Works fine for my NB200, even enabling/disabling bluetooth via /proc/omnibook/bluetooth
You should use ectype=12 instead of ectype=14. That way you can enable or disable wifi without needing to boot Windows. Unfortunately, the hotkeys don’t work, so you have to manually echo either 1 or 0 to /proc/omnibook/wifi (or if you prefer, just disable it in the bios when you want to be sure it is disabled).
To summarise (in Ubuntu):
  1. Download…1217-1_all.deb
  2. Install the omnibook-source .deb file, module-assistant and build-essential.
  3. Run module-assistant on the omnibook-source package.
  4. Load the module with ectype=12.
  5. Turn the Wifi on and off with /proc/omnibook/wifi

As root:

# This will install any dependencies not already on the system:
apt-get install bzip2 debhelper dpatch kernel-package make module-assistant build-essential
mkdir /tmp/omnibook
cd /tmp/omnibook
dpkg -i omnibook-source_2.20070211+svn20071217-1_all.deb
m-a a-i omnibook-source
modprobe omnibook ectype=12
echo 1 > /proc/omnibook/wifi

If this works as advertised, go ahead and add “omnibook” to the end of /etc/modules and “options omnibook ectype=12” to /etc/modprobe.d/omnibook.conf.

To disable the wireless adapter just use the command “echo 0 > /proc/omnibook/wifi”. To enable it, replace the “0” with “1”.