Did you manage to solve the problem eventually?
I would also like to make use of the 30pin bus on my hero4 black collecting dust for more than a year now. I need a remote/kind of security camera for my sailboat, which I leave alone for weeks sometimes, I thought the gopro could be of use here.
The power should be provided by a solar panel, which means no 7/24 service and the camera has to wake up when there is enough power.
The problem is, that the firmware seems completely useless for the task, the camera can't be turned on automatically after the power is reestablished, battery is charged. Worse, the wifi, configured to be ON, doesn't come back if I turn the camera back on manually. A working controller using the 30pin
connector could be the only way to do this.
It should be possible, because there is a Dash controller on the market using the 30pin connector and doing exactly what we need. (Cam-do) A bit pricey though for a remote...
It seems the signals are proprietary though, I see unsuccessful building attempts everywhere, i.e. grounding the power ON pin doesn't power on the camera...