I purchased a 5 pack of Emakefun Arduino Nanos on Amazon. I'm looking at the datasheet for the nano and I see that the voltage in is 6-20V.
The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.
I plan on using my car's 12v (14 when the engine's running) source to power the arduino. Which pin is pin 30? Are they referring to the Vin pin? I'm not going to be drawing much current, just enough to power up a 3 digit 7 segment display and to open up a transistor that drives a solenoid.
Correct, it's the pin marked VIN.
I’m not going to be drawing much current, just enough to power up a 3 digit 7 segment display and to open up a transistor that drives a solenoid.
Well, if you expect to drive the (multiplexed) 3 digit 7 segment display at 10 mA per segment and it shows all zeros, that alone will be 60 mA and that just as likely is too much for the internal regulator on a Nano to supply when fed with 13.8 V.
Much better to go buy a “buck” regulator module to provide 5 V.
A cigar lighter socket USB supply will get you 5V directly, and ought to filter out all those shockingly
large voltage spikes a car's 12V can exhibit...
You cannot assume a 12V automotive supply is even remotely clean.
6-20volt for Nano (clones) is a big fat lie.
There have been many reports of people blowing up nanos with 12volt, and not only from too much current draw from a pin. I would recommend to stay in the 6-9volt range for the V-in (raw) pin.
Powering the Nano with a 5volt buck converter on the 5volt pin or on the USB socket is good advice.
Take care if powering through the USB socket with a USB car cigarette lighter charger.
If you do, you can’t draw more than ~400mA from any pin, because of a <=500mA diode in series with the USB supply.
The Nano also runs on ~4.6volt when powered that way, because of that (schottky) diode.
Post a diagram, showing how/what you want to connect to your Nano, and how you plan to power everything.
I have my nano running in my car I used a fixed 5v regulator to get the voltage down to 5 volt. You van use regulated this 5 volt to power the display instead of using the supply from the arduino.
Which pin is pin 30?
Packages and module pin numbering goes anti-clockwise viewed from the top. Assuming there is
a pin 1 marked you can figure this out (but beware packages with gaps in the pins - the gaps may
or may not be counted! - the classic example is a DIL reed-relay which is in a 14 pin package with
10 pins missing typically)
In particular any DIL package is numbered this way, especially if on a standard pitch spacing
such as 0.3, 0.4 or 0.6", since this is compatible with standard DIL IC's and their sockets which
will have a footprint predefined in every piece of PCB layout software...
The reason it is anti-clockwise seems to be for compatibility with thermionic valve base numbering
where the component side was the underside of the device (valve/tube)...