Corrected post: My lack of success with SDM previously was due to my ignorance of how to actually make my USB test script run on the camera. If I run this script on the camera:
@title USB Test
rem set to upload mode for 5 minutes to give me time to play
My /var/log/messages file does report a USB device is plugged in as soon as I run the script, and it also looks like it is unplugged 5 minutes (300 seconds) later.
During the time the upload_images_for command is running, I can indeed fetch files off the camera with gphoto2 and delete files, so it looks like I need three things:
A way to notice when the usb interface becomes active - this seems easy enough: Using dbus-monitor --system shows that I get broadcast messages when I plug in the camera, and the strings associated with the message even include the serial number, so it should be easy to identify right and left.
A way to have the usb connection plugged into the computer, yet still be able to toggle the power on and off.
A somewhat fancier script on the camera to not only take the photo, but turn on the usb interface briefly after the photo is taken (the time it takes to raise the platen and flip the pages should also be plenty of time to download the images).
These all seem doable, so I'd think I can automate pretty much everything on the computer end and trigger it all by clicking the mouse to interrupt the usb power (or even use some fancy gadget to toggle the power via computer control).
In fact, I should be able to use an existing program I have (xdbusd) to prototype all this nonsense:http://home.comcast.net/~tomhorsley/sof ... dbusd.html
Old, obsolete info from yesterday:
I've been playing with the A480 plugged into my computer USB port to see what happens, and running the recommended SDM build, as near as I can tell, nothing happens - it never looks to my computer as if a USB device was plugged in (though plugging it in does make it take a picture). Over on the CHDK forum thread on porting the A480, it sounds like some work on the USB PTP support has been done, and it may exist only on a development version of the CHDK software. I may try to figure out if I can download and test that and see if I have more success.
The best I could do now with the current SDM looks like leaving the card unlocked so when power cycled, it boots to normal A480 firmware. At this point, gphoto2 works fine, it can fetch the images and delete them on the SD card. Then I could manually boot the SDM firmware and take another batch of pictures.
More experiments are needed, but perhaps someday I'll be able to use a computer controlled relay to toggle the power on the USB line running from the computer to the camera, have the camera take a picture, then switch to USB mode long enough for the computer to download then erase the image, and go back to waiting for the next power toggle.
Or maybe Eye-Fi really is simpler