Board for Arduino Nano and more.....

I am designing a board to have an Arduino Nano, 3 stepper drivers (4988 type boards), and options for several servos. I have a +12V barrel jack to drive the stepper drivers, and an on-board 7805 regulator generating +5V from the 12V, along with appropriate filter caps.

I am a bit confused about wiring power to the Nano. I know that I can have +12V going to pin 1 so it can be powered without the USB connector to the computer, but what about the +5V pin (Pin 4 I believe). Since I have a +5V regulator on my board, should I connect the output of the regulator to this pin to drive it or should it be open and let the on-board regulator of the Nano drive it.

Since I have a strip of signals, +5V and ground for connecting servos, I have my regulator providing power to the Vcc strip for the servos, along with my board ground, but am unsure about the Nano +5V. Reading the Nano data sheet it seems like this is an input/output signal and I should connect my regulator output to it, but I don't want to blow up a Nano board finding this is wrong.

Any help and clarification would be appreciated.

By the way, I am using KiCad to enter the schematic and design the board, and this package seems like a great tool. A bit confusing at first, but that is part of the learning curve I guess. Proto boards are really cheap if they are smaller than 100mm square and double sided. Around $10 USD including shipping for 5 boards and good quality!

Have a look at the schematic from the Arduino and the documentation .

Vin connects to a regulator with 5v output to drive the micro etc . It also connects to the 5v .
So the Arduino can be powered by feeding a voltage to Vin OR to the 5v pin. If powered by Vin , the 5v pin can be used as a supply to low current devices .