How to protect a micro controller from wrong connections

I am new to the forum and electronics world too.. As i am a basically computer engineer not having enough knowledge in electronics. But have few basics cleared.

What is my intention :
To protect a micro controller even if end user connects "ground as positive" and "positive as ground". What i want to make sure is only "positive should go to VCC and ground goes to ground"..

So my question is :
Is there any DC component which can forward / output a fixed positive and ground ; even if user provides any combination to the input... I just want to make sure even if end user mistakenly connects positive as ground AND ground as positive.... my circuit or a component should always forward / output separate and fixed positive and ground outputs.

Thanking you so much

Hi,

An approach is to use a diode bridge rectifier at the supply input, but the bridge rectifier would cause a voltage drop of anything from 0.6V to 1.4V all the time.

Keyed connectors and no two alike, would solve simple
setup problems. But remember, "anybody who says it's
foolproof has underestimated the common fool" (or
some quote to that effect).

A P-MOSFET works well in this application as a low drop, ideal diode.
Connect the MOSFET source to the + supply, the gate to ground (-), and the drain to the controller power.
The MOSFET will conduct when the source is positive, with a voltage drop equal to the current times it's on resistance (which can be very low), but will block current if the source is connected to a negative voltage.

The P-MOSFET must be a logic-level type (maximum Vgs threshold of 2V or less) if the voltage is below 10V

Here's a discussion of its operation.