A quick question for the developers... how much control do we have over the backlight (or indeed any of the other LEDs, but the backlight is going to be easiest to use in this scenario)?
My thinking is this...
If I want to sleep for many hours (or indeed days), in order to capture a particular event or sequence of events, as we have seen, there is a problem, I need a very large battery, or I need to keep swapping the battery.
An alternative approach is to switch on the camera only when needed. To do this, I can switch the camera on and off with a microcontroller.
The controller of choice these days seems to be an Atmel (arduino and clones), but a PIC would be equally valid in this scenario.
These guys can sleep for extended periods and use next to no power, but they have a downside, no real time clock. You can add one, but that adds to the complexity.
Furthermore, if you run them in very low power mode, typically they run from their internal R/C oscillator. This means that they keep very bad time, typically the oscillator is only good for +/- 3% accuracy, which works out about +/- 43.2 minutes per day.
So, my thinking was this.. Let the microcontroller sleep for "about the right time" less 4%, then wakeup and ask the camera what time it is (The camera has a pretty accurate real time clock in it).
As I said, the camera up till this point has been powered off. The microcontroller switches on the camera with a FET or relay or whatever is appropriate. Once it knows the exact time, it switches off the camera again to preserve battery life, then it too sleeps for the remaining time less 4% and so forth until the error is insignificant.
The trouble is... how to let the micro-controller know what time the camera has. I want this to be an easy hack. Something anybody with an arduino clone can copy, so I cant split the camera open and solder on to the uart, 'cos this is not something your average joe would even consider doing.
Most people can however fire a relay or mosfet and a photo transistor and a resistor on to a couple of I/O pins on an arduino clone (powered from the same source as the camera for ease of construction).
With the right software tweaks on both ends, the camera can blink the data from the RTC and the microcontroller can listen.
So my remaining questions are, would anybody be interested in this if it could be done, how easy would it be to do, and can anybody think of a better way to do this?
(OK I lied about it being a quick question