I was doing some more work on the 3D model and footprint of the micro USB connector today. I made some adjustments to the 3D model based on new measurements of a couple of features and updated the footprint and silkscreen outlines accordingly. I have updated the PCB with the updated footprint and wired up about half of the PCB. The parts still to connect up are the pushbutton and the voltage regulator circuitry.

I was thinking of using a 78Lxx regulator, then thought about using a zener diode but I don't think it would work well due to the range of battery voltage from full charge to when it is too low to take pictures. The variation in load current would also make it unlikely to work well. It then occured to me that perhaps I can use the same voltage regulator that is used on the GPS receiver board. It uses a Micrel MIC5205-3.3BM5 low drop out regulator that can take input voltages up to 16V and output 3.3V at up to 150mA. It will have no problem handling the 5V to 6V input from the camera and the output voltage is well within the operational voltage range of the microcontroller. The current limit is no problem as the interface board should not draw even 25mA and that is when the LED is on.

I have updated the regulator listed on the parts list. I will add/update capacitors once I check the datasheet for the regulator and determine what I will need for this application.