Arduino Due and Vin, 3.3V and 5V power inputs

Question

I just want to confirm something before I wire up my first ever Arduino project and fry all the stuff I just spent money on.

It is my understanding that the Vin power input will tolerate a 9V battery and use voltage regulators to pare it down to either 3.3V or 5V (as different parts of the board require). So it is then my assumption that if I have a 9V battery running to Vin, that I could then connect a power wire to the 3.3V connector, and reliably get a 3.3V signal (and ditto for 5V), yes?

Or, is it that they are input jacks expecting either 3.3V or 5V signals? I guess I'm confused over this:

• Will Vin then power the 3.3V and 5V inputs, giving me access to voltage at that level; or
• Do I have to choose between 3.3V, 5V or Vin, and only use one of those to power my board (with the appropriate voltage level)

• Ignacio Vazquez-Abrams: Have you checked the schematic yet?
• smeeb: If you can provide a schematic I'll check it out and maybe it answers my question, but I'm so new to electronics, I may not even be able to make sense of it.
• Ignacio Vazquez-Abrams: All Arduino product pages link to a schematic for the board.
• smeeb: Then I would assume this is what you mean, in which case, I cannot at this exact moment make sense of it. And although I think I can guess your next argument, which is probably "Well then you need to learn how to read schematics, otherwise get out of electronics", I would counter-argue that Arduino is from the ground-up aimed at complete electronics newbies like myself. And that this is a basic usage question that should be answer-able without a moderate understanding of EE/ECE.
• smeeb: And yes, in time, I will learn this stuff, but I shouldn't have to be able to read that diagram and fully comprehend it to understand how to connect my board to a battery.

Answer 1

DC Jack is connected, through a diode, to Vin.

Vin is stepped down to 5V on-board.

5V is stepped down to 3V3 on board.

Thus you can do any one of the following numbered items.

1. Connect a 7-12V supply to the DC Jack; thus:

   • use Vin as a supply @ DC - 0.7V for off-board peripherals, and
   • use 5V as a supply for off-board peripherals, and
   • use 3V3 as a supply for off-board peripherals.

2. Connect a 6-12V supply to Vin; thus:

   • use 5V as a supply for off-board peripherals, and
   • use 3V3 as a supply for off-board peripherals.

3. Connect 5V supply to the 5V; thus:

   • use 3V3 as a supply for off-board peripherals.

The above is only guaranteed for boards that follow the reference schematic, as plenty of clone/compatible boards do. If you buy a cheap Chinarduino and something doesn't work, or the thing breaks, after following anything above then that's your tough luck.

Answer 2

Yes your assumption is correct you can power 3.3v and 5v items from those pins as long as you don't take more current than the onboard regulator(s) can supply