CHDK on Ixus 100IS

Written by vidarlo on 20100716 in english and hardware and Linux and software and tutorials with no comments.

CHDK is software for some Canon compact cameras, which allows somewhat more than the original firmware. Or rather – it’s a addon for the original firmware. Quite risk free.

On Ixus 100/SD780IS (can someone explain why canon insists on seperate names for EU and USA?), it is as of writing only a beta port – some flaws, such as the camera turning of in some conditions.

The manual for installing CHDK was not that great, with a lot of technical details missing in my opinion. Here’s what I did to get it working.

Manual load

To make the firmware update available in the menu, I had to put the camera into play mode (press the button to display pictures), enter the menu, set Lens retract to 0 mins. and restart the camera and go into play mode again. Pressing menu gave me the firmware update at the bottom. And it worked. But it’s quite slow way to ender chdk…

Automagic booting

For some reason, pressing ‘Make bootable’ in CHDK-menu did not work on this camera. I don’t know if it was because it’s a beta, or what the reason might be. I assume that you’ve already tested manual loading, so card is loaded with files…

Making the flash card bootable by hand was somewhat a hassle, as the procedure was not documented in the FAQ or Howto from CHDK. Except the mac guide for some reason.

It turns out that I had to edit the boot sector of the memory card. This is not for the faint of heart… Grab a copy of your boot sector with dd if=/dev/mmcblk0p1 of=bootsector bs=512 count=1. Replace mmcblk0p1 with whatever device the first partition of your memory card happends to be.

Open the file in your favourite hex editor (ghex2 or emacs for instance). Now, replace byte 64-72 (or 40-48 if you count in hexadecimal) with the value ‘bootdisk‘.

Write your modified boot sector back to the card with dd if=bootsector of=/dev/mmcblk0p1 bs=512 count=1, eject the card and flip the write protection switch. Power on your camera. Enjoy the glory.

My impression so far…

Ok, shooting in raw is quite nice. It means a chance to manipulate colour balance after the photo is taken. It gives a lot of possibilities originally out of range on a compact camera.

But the by far coolest thing is motion detection. The possibility of scripting, and controlling the camera with scripts is certainly nice 🙂

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