What are the specifications of the dual voltage controller of the Ender 3/CR-10? Following on from What level of voltage does the Creality Ender-3 run at?

Dave's answer states that both 12&nbsp;V and 24&nbsp;V can be used on the controller board. It also goes on to say that the controller board is used in both configurations in two different printers:


Ender 3 and;
CR-10


I would like to know how this dual voltage operation works:


Does it use both voltages at the same time, or either one or the other? 
Are there two different electrical inlets or are they the same?
Does it auto-detect or are there jumpers used to configure or are the components tolerant to both voltage levels? 


Also related:


What is the board used? 
Is the board a proprietary design or a standard third party board? 
Does anyone have any photos of the board and/or schematics?
I own the Ender 3, and it runs on 24V, as this photo of the power supply shows:


From power supply  to the board, it uses a 2-wire line connected with a XT60 plug/jack that is common on RC cars:


The board itself is a proprietary design and labeled as "V1.1.2". The Voltage in is the lowest input on the left:


The Cooling fan (blue-yellow wire), the hotend cooling fan, heater cartridge (white shielded), bed heater (left black-red), board cooling fan (middle red-black) run (in this setup) on 24V. The Logic connectors (black-black &amp; White-white) run 5V logic. I could not figure out the voltage of the stepper motors (upper row).

I have not figured out how the power management circut works, but it achieves this:


Supply voltage $ U_S = 12V \lor 24V $
Logic Voltage $ U_L = 5V $
Sensor Voltage $ U_{sens} = U_L$
Hotend Cooling Fan $ U_{cool} = U_S$
Hotend Heating Cartridge $ U_{hot} = U_S $
Heatbed $ U_{bed} = U_S $


The chip's caption can't be read on the photo, but it is labeled as "Δ ATMEL // ATMEGA1284P // AU 1726"

For the pinout, a german maker did determine, that it the configuration of a Sanguino equipped with an Atmega1284P 16Bit works for compiling firmware and flashing via a bootloader.