GPA 2.1 finished build with review and some general questions

[Flavor]

There's a readme with the SD image. It talks about the hotkey stuff.

HOTKEYS

The system now uses a “hotkey” to enter a state where each button has an alternate function. Usually, in most RetroPie builds, this hotkey is pressed at the same time as the button. A might do one thing, and HOTKEY+A might do another. With the GPA, we are now using the power button as a hotkey. It can be difficult to hold the power button and another button at the same time (especially since the power button can also shut down the GPA).

In the GPA, the power button acts as a hotkey TOGGLE. Pressing it once (and quickly releasing it) puts the system into hotkey mode. Pressing any other button then does the hotkey function for that button. To exit hotkey mode, press the power button (and quickly releasing it) once again, returns the system to normal button mode.

In Hotkey mode, here are the button mappings.
X - Emulator menu (this is likely the most useful, as it gives access to other functions while pausing emulation)
B - Reset (exits some emulators)
R shoulder - Save current state to current slot
L shoulder - Load state from current slot
R dpad - Increment current slot
L dpad - Decrement current slot
SELECT+START - Exit emulator (some emulators only require HOTKEY+SELECT)
See https://github.com/RetroPie/RetroPie-Set...ad-hotkeys and /opt/retropie/configs/all/retroarch-joypads/GPIOController1.cfg

One issue is that, sometimes (usually the first time you use the hotkey toggle), you may need to tap it twice. At bootup, it can get in an odd state.

Another thing is that the hotkey stuff only works in emulators that support it. Usually the LibRetro emulators will. They will be named with the "lr-" prefix.

BATTERY
Where the green power light is, you should see a red light when the battery is low.

Please see http://forum.freeplaytech.com/thread-4418.html for more info about specific batteries.