Mount 360 degree rotator with camera using 2 pins

[COLOR=#242729][FONT=Verdana]I am designing a rotator circuit which consists of a 5v stepper motor and 5v DRV8834 driver I Center link description below here. The driver IC got 1 pins which is a step to control the motor. The problem/question is that only a two lines come from the camera top section. The camera top section runs at 12V. Is that possible to use the same 12V line to toggle as a 5V step pulse as well? The idea is as soon as the bottom section is connected to the top section, the Intelligent circuit should recognize whether the rotator is receiving 12V power or 5V step signal. If it is 12V then the system stays on and shouldn't consume current as well doesn't harm the motor. When it receives 5V step signal it goes through the 5V buck regulator (only if needed?) and supply the voltage to the motor and turns on the rotator. Is that possible to connect? I have attached the rough block diagram. Could you please help me.

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[COLOR=#242729][FONT=Verdana]Thanks in advance.[/FONT][/COLOR]