I would like to try CHDK on my A550 as indicated here http://chdk.wikia.com/wiki/A550.This
camera doesn't have a slide switch as spotted on some other canon models. I've created a ver.req file but I'm having a problem starting the camera in playback mode, the only way I can see to do this is to have a USB cable plugged in when turning on, and as far as I can tell this is still turning the camera on in record mode and then switching on playback mode as the key sequence required to extract the firmware version is ignored.
My goal is for gphoto2 to capture images over the USB connection, the standard A550 firmware doesn't support this. However I believe CHDK might, if the A550 doesn't have the timing issue documented somewhere else in the wiki that I spotted regading CHDK and capture mode.
Anyway if someone can point me in the direction of turning on in playback mode , that would be a start.