(Sorry, I'm extremely new to Arduinos) I have an LED strip that requires 12V, but I think the Arduino Uno only does 5V. After reading around, I was curious about how the 'Vin' pin worked... If I connect a 12V battery to the Arduino via the 'Vin' thingo, do all the digital pins become capable of outputting 12V? Or will that just fry the circuit?
I guess I should be asking, what exactly does the Vin do? What is the purpose, or how is it utilized?
(I know there's a way of powering the LED strip with relays and external power, but I've currently run out of relays, so I'm tryna be creative.)
Vin is regulated down to 5V internally, everything else is strictly 5V. Vin is solely to allow powering from a source greater than 5V (well, greater than 6.5V actually). For instance you might have a 7.4V 2S LiPo power source - that could go to Vin.
The microcontroller pins will fry if exposed to voltages over 5.5V or less than -0.5V (powered up), or outside the range -0.5V to +0.5V when powered down.
Hmm ok. Hypothetically, if I did plug a 7.4V LiPo power source into the Vin, would I be able to power a motor that required 7V? From my understanding of your reply, the pins would instead be fried?
No.
7.4V to VIN is regulated down to 5V. This 5V is used by the chips.
The Arduino is a controller NOT a power supply! Don't try to run anything more than a couple of LEDs from the board, if you do, you risk damaging the main chip.
You can run external things, using an external Power source, as long as you connect the grounds, and if the control signals need higher than 5V, you would need to use a transistor/MOSFET to do the voltage conversion.
ViN stands for Voltage In for ARDUINO UNO Board. It only powers the AtMega328P chip and the other peripherals on the board. If you want to power a 12V motor, you have to supply power to the motor externally and then you can control the speed and direction of the motor using 5V control signals.
For that please refer this diagram (click on it):
You can clearly see that external power is being supplied to the motors. But there is a common GND.
Unfortunately, and I realise this is due to misleading information on the Arduino website (and others), you appear to be mistaking the "Vin" pin for something useful!
Arduino I/O pins are not power sources. They are digital logic signal outputs. They are designed to provide up to 20 mA. the 40 mA specification is an "Absolute maximum" or danger warning. You do not "power" anything from I/O pins - other than a LED with a current limiting resistor for 20 mA. You use the pins to control transistors or (preferable) "logic-level" FETs to switch on motors or such things.
