In the Electrical and Computer Engineering Deaprtment of the University of Auckland, where I work we have a little device, internally known as the ‘DonKey’. The purpose of this is to allow easy programming of Atmel AVR based microcontrollers via USB, rather than the simpler serial interface. We also have some internally developed software to program microcontrollers via the device, unfortunately this software is pretty much windows only (we did have a successful attempt to compile it for Linux, but this was quite a while ago, a better solution would be to use a native Linux application).

Internally the DonKey uses an FTDI based USB to UART chip (specifically the FT232R) to communicate with the microcontroller. This presents some problems as, despite being the basis of the programmer on incredibly popular Arduino boards, the main Linux programming tool (AVRdude) has no official FTDI support. I think this is largely due to the use of a bootloader on the Arduino boards, which negates the need of the programming tool to directly flash the board. If however you brick the AVR on the Arduino, you would be out of luck and would need a physical programmer (more on this below).

The DonKey in all it's glory.

In this howto I’ll cover how to get the DonKey working on Linux with AVRdude. Luckily, while researching how I might go about this I found that a large part of the work had been done for me, due to the fact that the Arduino also uses these chips. I found instructions on doswa.com on how to patch and compile AVRdude for just this purpose (so you could flash a bootloader to a new AVR).

These instructions work quite well for the DonKey, up until you get to running the ‘./configure’ command, I replaced this with:

$ ./configure --prefix=$HOME/.local

to setup the code to do a local install in my home directory (as I want this to be my primary version of AVRdude, but not to screw with things on the root filesystem).

Next I followed the instructions on modifiying the makefile and compiling AVRdude via the ‘make’ command. After ‘make’ I also typed:

$ make install

to install into the directory setup earlier. Now AVRdude is installed, the next thing to do is a bit of configuration, firstly you’ll want to make sure it’s on your $PATH so add the following to your ~/.bashrc file:

export PATH=$HOME/.local/bin:$PATH

and run the command:

$ source ~/.bashrc

to re-read the file.

The next issue is that you may wish to remove any copy of AVRdude that is otherwise installed (I found that sometimes my shell would run the wrong one – especially if you use ’sudo’ to run it):

sudo apt-get remove --purge avrdude

Now, I just mentioned above that you might use ’sudo’ to run AVRdude, well according to the doswa article you do need to use sudo when using the FTDI based programmers. I’m not sure why this is, but it’s not very useful if you want to be able to call AVRdude from a Makefile or the like.

I solved this by setting a ’suid root’ on my AVRdude binary. For those that don’t know what this is, the suid bit is a Unix permission setting that makes any program with it run under it’s owning user rather than the user who called it. If the owner happens to be root, the program runs as root even if the user who calls it isn’t. This is probably really insecure if you do it a lot, but you should be OK in this case.

WARNING: Despite what I say, it might not be OK. Allowing any program unrestricted root access has the potential to hose your system and scatter all your data to the winds. FOLLOW THESE INSTRUCTIONS AT YOUR OWN RISK!!

So here we go:

$ sudo chown root:root ~/.local/bin/avrdude
$ sudo chmod u+s ~/.local/bin/avrdude

Now you should be able to successfully run AVRdude on FTDI based devices without resorting to using sudo every time.

But, what of the DonKey I hear you cry! Well all we have to do to support the DonKey is give AVRdude a little bit of configuration which tells it what the DonKey actually is. This can go in ~/.avrduderc, and looks a bit (well exactly) like this:

programmer
id = "donkey";
desc = "University of Auckland ECE DonKey";
type = ft245r;
miso = 1; # D1
sck = 2; # D2
mosi = 3; # D3
reset = 4; # D4
;

OK, now you should be able to successfully use the DonKey with AVRdude, using a command similar to this:

avrdude -c donkey -p m8 -P ft0 -U myawesomeavrproject.hex

Note: this command is for the ATMega8 as denoted by the ‘-p m8′, check the AVRdude manual page for the correct -p option if you are using a different type of AVR.

OK, well that’s pretty much it, I’ll post back soon regarding my other progress with some microcontroller stuff. Bye for now!

I’m very pleased to announce the release of my pet project Mu-Feeder, or at least a very early version of it. I actually released version 0.1.0 unofficially yesterday, but then found a bug which was tickled by Python 2.4, so fixed that and re-released as version 0.1.1.

If you want to try it out you can get it here, or you can download the code with:

$ bzr branch lp:mu-feeder/0.1

If you have a bug report, please post it on the Launchpad bug tracker, I’m also seeking feedback which you can send to me in a variety of ways (comment here, identi.ca or Launchpad answers page).

I hope someone finds this useful! Enjoy!

The purpose of this entry is to announce my personal Free Software project. Mu-Feeder (pronounced ‘mew-feeder’) is a project to replace the proprietary web service Twitterfeed with a piece of Free Software. Basically the idea is to take entries from an RSS or Atom feed and post them to a microblog. I figured this could be quite easily done and it would let me get used to the tools, etc involved in publishing Free Software. Basically, it’s not meant to be a complicated project, just to fill a gap and give me some experience.

At the moment the software is designed to run as a Python script executed via Cron. When it gets called it should build a summary of the top items in the feed (along with shortened URL’s) and post them to the configured microblog. I already have identi.ca support as well as (untested) twitter and StatusNet support, principally bacause they all use the same API. I’m aiming to have support for a single feed in the 0.1 release with support form multiple feeds in a subsequent release.

All the details are up on the Launchpad page at https://launchpad.net/mu-feeder and you can get the code via bzr with:

$ bzr branch lp:mu-feeder

Bug reports are welcome at https://bugs.launchpad.net/mu-feeder.

That’s about it, I’ll update on progress here as I go. Bye for now!

PS. Ironically this blog entry will be posted to identi.ca with the very service that Mu-Feeder aims to replace!

The following commands will resize an ext2, ext3, or ext4 filesystem running on LVM while it is mounted:

$ sudo lvresize -L +XXG <path to fs device>
$ sudo resize2fs <path to fs device>

In the above command you need to replace XX with the number of GB you want the filesystem to grow by and <path to fs device> by the device node (typically /dev/mapper/something).

An there you have it, done! Obviously there is a huge amount more you can do with the two tools above, take a look at their man pages for more info.

Hopefully this post will save me from having to work out how to do this every time!

The responder was Stephen Sharon via Twitter, he’s written a paper around some of the legal concerns over turnitin and he sent me the link. It’s good reading and confirms some of the things I had heard surrounding the site. I’d encourage everyone reading this to click through and read Stephen’s paper (it’s 38 pages, but double spaced and with much of each age containing references).

I’m not qualified to give legal comment on tunitin (I’m and Engineer not a Lawyer), but I will give my opinion. Before I do I’d like to give the following disclaimer (in true Software Freedom Law Show style):

WARNING: The following DOES NOT (in any way, shape or form) constitute legal advice, it is only my own (perhaps misguided) opinion. I would urge anyone who has any concerns over how their data may have been used by Turnitin to contact someone who actually knows what they a talking about, in this case A LAWYER!

Basically, I think Turnitin is on pretty shaky legal ground both in terms of Copyright and Privacy (certainly under US law). Here I New Zealand we have different privacy laws, but I’m sure they probably say much the same thing. The copyright issues are also concerning, I don’t want to turn over my rights to Turnitin just so I can submit my paper. What if my assignment gave technical details of an invention which I may in future have some financial interest in. Turnitin would have the right to use that information as they see fit.

Realistically I think it’s only a matter of time before Turnitin is taken to court again to face a hard examination of their user agreement, etc. This whole thing brings be back onto the subject of Free Software. I think it really is important for these tools which have such important uses to be Free (as in speech), it would be great to see a Free Network Service replace Turnitin as the dominant player in this market. I would much rather trust that to be transparent and honest than a company driven by profit and market share.

Anyway that’s just my $0.02. Before I finish I’ll encourage you all again to read Stephen’s paper.

Bye!

I’ve also been working generally on my ‘personal cloud’. I’ve put up a gallery where I can put my photos which is something I’ve wanted to do for a while. I’m using Gallery 3 (Beta 3) which is nice. I tried this a while ago with Gallery 2 and it was horibly complicated and overengineered so I gave up in the end.

The new interface is really nice, there’s come nice AJAXy stuff in there which makes it feel nice and polished – kind of like using Flickr or Facebook only with Freedom. As you may have gathered I’m not a huge Facebook fan, although I do have an account, this is mainly because of concerns over privacy and what control they have over your data (including any photos you upload). I’d rather just retain control and ownership of my data.

Anyway if you want to have a look at the gallery, click the gallery link at the top of the page (it currently uses javascript to redirect you – something which I will fix in future). I think that’s about all for now. I’m hopefully going to get back to posting some techy stuff soon, I still have a couple of things lined up I just haven’t had time to write them up yet.

Bye for now!

When I logged in I got a message warning me that it might not work, but I honestly don’t see the reason why. Shouldn’t it just be browser specific, not OS specific? I then proceeded to upload my PDF and it seemed to think it actually wasn’t a PDF! Switching to a Windows XP machine and uploading the same PDF worked fine which is the really random thing.

I don’t even see why our University has to use a third party service for this anyway, I’m sure they have the resources to do this in house. Then there is the whole copyright thing, which I’m not altogether happy with either.

Anyway, at least it seems Ubuntu isn’t alone in this, according to a friend Windows 7 also triggers the same error message (albeit without the PDF fail).

Again, sorry for the rant.

For anyone that doesn’t know, I’m studying Computer Systems Engineering at the University of Auckland and I’m in my final year of undergraduate. At our university that means working on a year long project (worth 2 times the credit of a regular course) and presenting your progress at the end of it. My project was in the embedded systems arena and involved the development of a real-time embedded speech dialogue system – basically an embedded speech controlled application. I’ll try and post some more details in the future, I have some videos and stuff I want to put up, but I don’t want to focus on it too much because we didn’t really use that much Free Software.

Anyway, it’s pretty much over now – we just have one more component to hand in on Friday and then it’s done. I’ve really enjoyed the experience and learnt a lot. I’m thinking that I may go further into embedded systems – hopefully to do a Masters degree next year. I also want to do some hardware hacking/embedded systems stuff at home and have already been searching out how I can do it using Free Software, I’ve already found Free replacements for some of the components we used which I wish we’d used now! Maybe there will be a few posts on that in the future, but I already have a couple of other posts lined up, so expect to see a flurry of activity here!

That’s it for now though. See ya!

The main piece of software you will need is dnsmasq, which you can install with the command:

sudo apt-get install dnsmasq

I already had this installed as I’m using it as a DNS cache for my network (which is also pretty useful). It turns out that dnsmasq is a bit of a ’swiss army knife’, it can do DHCP, DNS and TFTP all together and very easily. You should edit the config file:

sudo nano /etc/dnsmasq.conf

And add/uncomment/edit the following lines:

dhcp-range=192.168.1.3,192.168.1.50,12h # sets the ip address range and update frequency for the network
dhcp-boot=pxelinux.0 # set up network booting to boot the pxelinux bootloader
enable-tftp # enable built in tftp server
tftp-root=/var/tftpd # set tftp directory

Basically this sets up dnsmasq to be both the DHCP server for the network and push the PXE boot options out over the network. It also enables the built in TFTP server in dnsmasq and sets the directory to serve files from.

The next step is to get some files to serve, I got the PXE/netboot image from the Ubuntu cdimages site, and untarred the files to the correct directory:

wget http://archive.ubuntu.com/ubuntu/dists/jaunty/main/installer-i386/current/images/netboot/netboot.tar.gz
sudo mkdir -p /var/tftp
tar -xvzf netboot.tar.gz -C /var/tftp/
chown -R nobody:nogroup /var/tftp

The tar file of course is basically just the minimal install CD, set up for netbooting, so when you install you will need to download all the packages, for a simple cli install this doesn’t take very long, and you can use a package cache or something to help with future installs.

OK, now restart dnsmasq:

sudo /etc/init.d/dnsmasq restart

…and you should be good to go (make sure that your machine is the only DHCP server on the network). For tips on booting clients see my original article – btw, since I used the new version of Ubuntu I can now boot my Eee PC 901 over the network!

If you have any questions or problems with this I’d be happy to answer them, just post them below.

Bye for now!

But it is kinda static. By this I mean it’s not particularly suited to environments where things change frequently. For example, we have a local mirror at uni, which of course it much faster than using the external Ubuntu or Debian ones, however as this is only available from internal University of Auckland IP addresses I would have to change my /etc/apt/sources.list file if I wanted to install something from home.

Today I knocked together a quick Python script to fix this, all it does is basically manipulate a symlink which points to the real /etc/apt/sources.list file, but I thought I’d share it anyway:

#!/usr/bin/env python
import sys, os
def usage():
print "Usage: %s " % (sys.argv[0],)
def main(argv):
if argv[1] != None:
sources_path = "/etc/apt/sources.list.%s" % (argv[1],)
if os.path.exists(sources_path):
os.unlink("/etc/apt/sources.list")
os.symlink(sources_path, "/etc/apt/sources.list")
print "SUCCESS: Don't for get to run 'sudo apt-get update'"
return 0
else:
print "ERROR: Unknown repository set '%s'" % (argv[1],)
usage()
else:
usage()
return 1
if __name__ == '__main__':
sys.exit(main(sys.argv))

Unfortunately wordpress screwed with my formatting there (which kinda matters in a python script) so here is the file (repo-switch.py). You’ll need to download it and put it somewhere in your $PATH. Then make it execuatable:

chmod +x repo-switch.py

The next step is to set up your lists of repositories. Each list will have a suffix which the script will use to identify it. First I copied my main repositories (for the NZ Ubuntu mirrors):

sudo cp /etc/apt/sources.list /etc/apt/sources.list.nz

Obviously replace ‘nz’ with a suffix of your choice. Then I dropped the list of repos for the local mirror into another file (in my case /etc/apt/sources.list.ece). You can set up as many different sets as you like, but I only need two.

Next step is to practice switching between them:

sudo repo-switch.py nz

…sets apt to use the file /etc/apt/sources.list.nz by changing /etc/apt.sources.list to a symlink pointing to the relevant place. Calling the script again with a different set (e.g. ‘ece’ in my case) will set it up to use one of your other sets.

Obviously, you’ll need to run ’sudo apt-get update’ each time to make apt work with the new repos, but I added a line to the script to remind you!

Magic!