My team has been working on a prototype for a device that sits on a DSLR or mirrorless camera, connects to the camera via usb and allows the user to control the camera over wifi or bluetooth. We've been using the Intel Edison. We would like to get a custom pcb designed that connects to the edison through the 70pin connector and provides the following:
1) usb 2.0 micro OTG port
2) LiPo charging circut, powered via a 2nd 5v usb micro plug
3) boost circuit to give 5v to the usb OTG port
4) on/off switch accessable from the side of the board (surface mount)
5) power led which can be disabled by a pulled high gpio pin (surface mount)
6) another led connected to a gpio pin (also surface mount)
Most of what we need is already available in the following sparkfun boards:
Both of the boards above have eagle files available as a starting point.
Just to clarify a few things:
1) the board must power the edison from the battery, 2nd usb power port, and seamlessly transition between the two without loss of power to the edison or usb.
2) the board must charge the lipo battery when power is available from the 2nd usb power port.
3) the board must charge at 500mah when available from the usb connection (I understand there's some ways to request even more power from usb to make it charge even faster, we will most likely have a 1C 1000mah battery, so faster charging is a plus if possible)
3) the board must provide 5v to the OTG usb connection (otherwise some camera's won't connect)
4) the board must have a led that lights up when the power switch is enabled unless a specified gpio pin is pulled high. (So normally the light would light up, but we could disable it from the software while running if needed)
The sparkfun boards should be a good starting point, they also have a template for intel edison "block" you could look at (https://www.sparkfun.com/news/1591) Though you might be better off looking at the base block as a starting point.
Lastly, included as part of this project would be helping me through the process of getting the prototypes and board manfactured. For the prototype version, we expect to only need about 20to 50 of the boards. Later versions may require a larger number of boards, but helping with that can be considered part of a seperate job. One thing to keep in mind is that edison's 70pin connector is kind of a weird part and I'm not sure all manufacturing houses can handle it.
One last feature, while not a requirement, would be a "nice to have" option. (So let me know if its something you can do) Some camera's can charge or be powered through the usb port. Ideally it would be nice to be able to plug the board into another usb power source (portable usb power bank for example), and charge/run the camera at the same time.
Pleaes hit me up with any questions or things I need to clarify.