I thought it is time to summarize where the project stands and to state what I will be doing next towards having a working prototype.

I have a preliminary schematic for the interface board that sits between the camera and the GPS receiver package and I have started work on a PCB for it. I included an optional programming header for the AVR microcontroller to aid in development of the prototype. Once the software is finalize for the AVR microcontroller I won't need to install the header on any later copies of the project that I might make.

I need to locate and order a mini and micro USB connect that I will use for the project. I've been thinking I would prefer to use a through hole part for the main mini USB connector rather than a surface mount part. It would give me more mechanical strength and stability than a surface mount part. It could increase time between failures as the connector might be subject to a certain amount of stress from the cable that will be connected to it during use.

I hit a minor problem that will require adding some extra parts to the PCB. I need a voltage regulator to drop the camera battery voltage down to a safe level for the interface board and GPS package. I also may need to add a transistor and resistor to buffer the GPS data output from the AVR microcontroller that feeds the camera to make sure the signal level is high enough for the camera to recognize the data.

My next step is to put together a proof of concept that will let me see GPS data on the camera. To do this I will send a command to the GPS package to drop the baud rate to 4800. If I can't do that I will have to write a program for the
AVR microcontroller to receive GPS data at 9600 baud and feed the GPSGGA data at 4800 baud to the camera. I will wire up a simple buffer where I can alter the signal levels that will feed the camera. I don't know if the input to the camera is only good for TTL levels or not so I will start by being conservative and increase the output level slowly until I see the camera indicating it is receiving GPS data. To be safe, I will not exceed 5V on the input to the camera.

Once the camera shows it is receiving GPS data it will confirm I'm on the right track and the rest is down to finalizing the interface board design and packaging.

I'm close to a working proof of concept. Seeing GPS data appearing on the camera will be an exciting moment.