Hacking an Olympus Mju 300 Camera
WARNING - Digital Cameras have large capacitors which often are charged (and remain charged for long periods of time) - they really hurt if you discharge them through yourself and will destroy chips!
Olympus Mju 300 Digital Cameras are 3.2MP cameras that are suprisingly good cameras to hack up, they have 3x optical zooms, Li-ion batteries, accept XD cards (slightly annoying) and have IR remotes. But the best thing is that the on/off switch (which is activated by sliding the cover back) breaks very easily, these models end up on ebay - however this is easily fixed.
Opening the Camera
Step 7 - Careful pull everything apart, avoid touching the capacitor (its quite well hidden in this model), the on/off switch is just above the IR receiver, a blob of super glue can keep this stuck down and always on.
This is the IR transmitter, I haven't yet adapted it but the plan is to bypass the on switch with a wire soldered between so that the transmitter is always on and remove the 3v cell instead replace this with power supplied by a GPIO. Just turn the GPIO on, it powers the transmitter which triggers the camera to take the picture.
Wiring the shutter switch
We are going to bypass the shutter switch on the top of the camera (the push button on the left of the camera). The theory is that the camera runs at 3v (check with a multimeter) and when the push button is pressed it connects a circuit which triggers the camera. So instead of linking the circuit, we attach a GPIO to one side and the other side to GND, when we toggle the GPIO high (2.8v) it'll be as if the button had been depressed and trigger the camera.
In this case the push button has 5 contacts, 2 on the left and 3 on the right. Through some trial and error I found that if you link the two contacts on the left together and then briefly touch the joined wires to the top pad on hte right you simulate the button being pressed and the picture is taken. Attaching this to the flight computer will again need a little bit of work (either use a multimeter to work out which wire should be the GPIO and GND or by a little bit of risky trial and error) but we should now be able to control the camera from the flight computer, toggling a GPIO high briefly, triggering the shutter.