Homebrew Remote Switch For Canon EOS-350D

I’ve found myself needing a remote switch for my Canon EOS 350D camera recently. The official Canon product is the RS-060E3, but at 25 UKP that seems a bit steep.

A quick search on Google, and I came across Chantal Currid’s page on making your own remote control.

It turns out it’s actually really simple to build my own, so that’s exactly what I’ve done.

The EOS 350D uses a 2.5mm stereo socket, the three connections being ground, shutter control and auto focus control.

A quick trip down to the radio studios are work produced an old stereo cable from their junk box. This had a 3.5mm stereo jack plug on it. Next was a trip to Maplin on Great Portland Street where I bought a 3.5mm to 2.5mm adaptor plug, a handheld box, a red push to make button, a black push to make button and a toggle switch.

components

The wiring is simple, and details are on Chantal’s page on the theory of operation.

The toggle switch is used to latch the auto focus. The black push button is a momentary connection to the auto focus for when we don’t want to use the latch. The red push button is used to trigger the shutter release. If the toggle switch is on, this keeps the shutter open until the toggle is switched back. Very handy for those long “bulb” exposures.

Here’s the wired up box.

wired up canon switch

And here’s the final finished (and working) remote switch.

finished switch 1

finished switch 2

finished switch 3

finished switch 4

It should be possible to do more interesting stuff with this. How about one of Maplin’s IR beam kits, that we can use to trigger a shot if an invisible IR beam is crossed? Or even fitting in one of their remote control units? There are a lot of cool ideas to try.

iTunes Now Playing In Perl

After working on the C# iTunes Now Playing program, I thought I’d give the Perl Win32::OLE module a try.

This module is Activestate Perl‘s COM interface for Microsoft Windows.

After using Perl for nearly 8 years, I’ve never given it a try before, and it turns out to be surprisingly easy to use.

The following script works exactly the same way as the C# version.

Firstly we need to create a new iTunes.Application object.

my $iTunesApp = new Win32::OLE("iTunes.Application");

Next we get the current track and print the name and artist.

my $track = $iTunesApp->CurrentTrack;
print "Current Track: " . $track->Name . "nCurrent Artist: " . $track->Artist . "n"

And that’s it. Obviously we should be checking to make sure the objects were create correctly, but this is just a simple example, not live code.

So to recap, here’s the final working example code.

#!/usr/bin/perl

use strict;
use Win32::OLE;

my $iTunesApp = new Win32::OLE("iTunes.Application");
my $track = $iTunesApp->CurrentTrack;

print "Current Track: " . $track->Name . "nCurrent Artist: " . $track->Artist . "n"

iTunes Now Playing In C#

I’ve been playing about with the COM interface to Apple’s iTunes running on a windows machine with .NET installed.

My choice of language has been C# as it’s a bit more Perl like than VB. I’ve used Microsoft’s “free” Visual C# Express in this case.

The iTunes SDK is available from Apple and has all the documentation needed.

I’m going to run through how to get Now Playing information out of iTunes. The quickest way to do this is as a console application.

Start up Visual C# and create a new console application. I called mine NowPlaying.

You’ll need to add a reference to the iTunes come library. Do this on the righthand side of the C# project window by right clicking and selecting “Add Reference…”, selecting the COM tab, and finding the iTunes library.

The first thing you’ll need to in your code is to import the iTunes namespace to make the code look a little cleaner. We’ll also need the System interface for our console input and output.

using System;
using iTunesLib;

In your Main method, the first thing we need to do is to create an instance of the iTunesAppClass. I’ve rather originally called mine, app.

// Create a new iTunesApp object to use
iTunesApp app = new iTunesAppClass();

Next we need to get the current track. This is a simple attribute call to the app object.

// Get the current track from iTunes.
ITTrack track = app.CurrentTrack;

Finally we need to show the current track. To do this we call two attributes on our track variable, name and artist. There are plenty of other attributes we could call, but these are the two most useful for this example. See the SDK for more choice.

Once we have displayed our name and artist, we need to wait for the user to hit return. This is useful if our program wasn’t launched from a console window as it would end before we’ve had a chance to read any output.

// Display some info on the current track.
Console.WriteLine("Current Track: {0}rnCurrent Artist: {1}" , track.Name, track.Artist);
// Pause until we hit return.
Console.ReadLine();

That’s it, nice and easy.

Here’s the full .cs source code.

using System;
using iTunesLib;
namespace NowPlaying
{
class Program
{
static void Main(string[] args)
{
// Create a new iTunesApp object to use
iTunesApp app = new iTunesAppClass();
// Get the current track from iTunes and return its artist and name.
IITTrack track = app.CurrentTrack;
Console.WriteLine("Current Track: {0}rnCurrent Artist: {1}" , track.Name, track.Artist);
// Pause until we hit return.
Console.ReadLine();
}
}
}

Acme::Terror::UK Update

I’ve updated the Acme::Terror::UK module to version 0.02 on CPAN and added a new method called level

The new level method returns the current UK terror alert status in an easily comparible format.

my $t = Acme::Terror::UK->new();
if ($t->level() == Acme::Terror::UK::SEVERE) {
print "The current terror level is SEVEREn";
}

See the documentation with the module for more information.

On the back of this, Andy Kennedy released Acme::Terror::AU. As the Australian government refuses to release this information, his module always returns Acme::Terror::AU::UNKNOWN. 🙂

Introducing Acme::Terror::UK

There is a lot of fuss in the press at present about the current terrorist threat to the UK.

The government has put the current threat level on a few of it’s websites. These are…

The US government has had provided it’s threat levels to the public for a while, and there are various ways to access this, incuding a Perl module called Acme::Terror.

Now the UK has this information online, I decided to provide the UK with it’s own version of this Perl module, which I’ve rather originally decided to call Acme::Terror::UK.

It’s really simple to use the module. For example, this small bit of code will fetch and display the current UK threat level.

use Acme::Terror::UK;
my $t = Acme::Terror::UK->new(); # create new Acme::Terror::UK object
my $level = $t->fetch; # fetch the current terror level
print "Current terror alert level is: $leveln";

The code goes off to the home office site behind the scenes and screen scrapes the page to get the current UK threat level as the UK government doesn’t currently provide and automated feed of this information. This makes the module vulnerable to any design changes on the page, but it works for now and that’s the main thing.

There are 5 levels, these are…

  • CRITICAL – an attack is expected imminently
  • SEVERE – an attack is likely
  • SUBSTANTIAL – an attack is a strong possibility
  • MODERATE – an attack is possible but not likely
  • LOW – an attack is unlikely

At the time of writing, Acme::Terror::UK informs me the current threat level is SEVERE.

Interesting Nokia Lifeblog Bug

Now here’s an interesting bug in Nokia Lifeblog application on my Nokia 3230 phone.

If you take a photo using the camera and then post it to the web using Lifeblog, it won’t then let you send the image via MMS. Instead, it complains “unable to send copyright protected item”, even though I own the copyright of my own picture.

This is running version 1.51.2 of the Lifeblog software.

Nokia’s Flickr Uploader Uses The Atom Protocol

Charlie has a photo of his back garden on his blog that was updated using the Flickr uploader on his Nokia N93 phone.

FYI, the ‘Flickr’ uploader is using the same protocol as Lifeblog. So, if you know how that is done, you can theoretically post to other Lifeblog compatible sites.

That’s really interesting, and I was pondering which protocol the Flickr uploader would use. Lifeblog uses the Atom protocol, and I have written code to take lifeblog entries and upload them to a blog in the past.

I just need to get hold of a nice new Nokia N93 phone to test my code still works with the new Flickr uploader.

Retargetting Selected Links With JavaScript

At work I have a new site that makes use of iframes to embed external content onto a page. The content is a blog, written by non technical members of staff who needed to be able to include links to external websites. They are happy with using <a href=" tags, but I didn’t want to worry them with target parameters in the HTML. We have to target _blank as we want the readers to keep the old site open and not open the content in the site framework.

The solution to this is to use a bit of JavaScript to manipulate the DOM and insert blank targeting to all blog entries.

As we control the HTML template of the blog, we made sure all the blog entries were wrapped by an enclosing div tag with a class called blogentry.

Here’s some example HTML. We have one link in the blogentry div we need to re target. The other link is not in a blogentry so has to be ignored.

<div class="blogentry">
<a href="http://www.robertprice.co.uk/">This link needs to open in a new window</a>.
</div>
<div>
<a href="http://www.robertprice.co.uk/">This link won't open in a new window</a>.
</div>

The JavaScript first has to get all div tags on the page. It does this by calling getElementsByTagName on the document. Once we have all the div tags, we have to iterate over them to make sure we only get the ones with the classname of blog entry.

var entries = document.getElementsByTagName('div');
for (var i in entries) {
if (entries[i].className == "blogentry") {
// insert target code here.
}
}

Now have our blogentry’s we need to find all the links inside and make sure they all target blank. We do this by calling getElementsByTagName on each node, then setting the target attribute to blank.

var targets = entries[i].getElementsByTagName('a');
for (var j in targets) {
targets[j].target="blank";
}

It’s as simple as that. The full code follows…

<script language="JavaScript" type="text/javascript">
<!--
var entries = document.getElementsByTagName('div');
for (var i in entries) {
if (entries[i].className == "blogentry") {
var targets = entries[i].getElementsByTagName('a');
for (var j in targets) {
targets[j].target="blank";
}
}
}
// -->
</script>

Using Series 60 Python To Talk To A Webserver

I’ve been continuing my journey into Python by modifying my earlier location script to now post details to my website when run.

I’m using the standard urllib now and moving to slightly more advanced Python language features such as dictionaries (basically the equivalent of a Perl hash).

The code gets the location, calls a CGI script on my website and prints the returned message from that script to the console.

Here’s the code…

# we need access to the location and urllib modules so have to
#import them.
import location
import urllib
# get the mmc, mnc, lac and cellid by calling the gsm_location
# method from the location module.
(mmc, mnc, lac, cellid) = location.gsm_location()
# add the location to a python dictionary called params.
params = urllib.urlencode({'mmc': mmc, 'mnc': mnc, 'lac': lac, 'cellid': cellid})
# open a filehandle to a cgi tracking script that takes
# the contents of dictionary params as parameters.
f = urllib.urlopen("http://www.robertprice.co.uk/cgi-bin/test/cellid.pl?%s" % params)
# get the results, hopefully a message saying OK.
print f.read()

All the CGI script on my website does is to record the parameters passed to it and return a simple text string saying it ran OK.

As you can see it’s really simple to Series 60 Python to communicate over the phone’s network connection. I have to say, this language is turning out to be better than I had expected, and far easier than J2ME.

My First Python Script

It’s a full day since I started to try to teach myself Python for my Nokia 3230 phone.

My first script is running, and though it isn’t anything impressive, I’m still very pleased with the results.

So what is this amazing script? Well it just gets the current location of the phone by CellID, using the location module supplied with Python, and displays it on the console.

Here’s the code…

# we need access to the location module so have to import it.
import location
# get the mmc, mnc, lac and cellid by calling the gsm_location
# method from the location module.
(mmc, mnc, lac, cellid) = location.gsm_location()
# print out the retrieved details to the console.
print "mmc %sn" % mmc
print "mnc %sn" % mnc
print "lac %sn" % lac
print "cellid %sn" % cellid

screenshot of the python location script results
As you can see it’s not going to win any prizes at PyCon, but it does provide some very practical information for me, namely my location.

But what are those 4 variables returned?

  • MCC = Mobile Country Code
  • MNC = Mobile Network Code
  • LAC = Location Area Code
  • Cell ID = The Cell’s ID 🙂

Stay tuned for more Python adventures over the coming weeks.