Arduino Pro Mini - multiple pins, same name


I’d like to clarrify a view points about the arduino pro mini.

  1. there are 4 GND pins. Should I be connecting ALL of them to ground? or just any one of them?
  2. ditto for VCC - there are 2 pins with the same name do they both need to be connected? (if they get used)
  3. Is the Vcc pin an input, output or both? I’ve got a 5v arduino pro mini, and I intend to power it from an existing 12v regulated source. The instructions indicate I can connect a 12volt (max) supply to ‘Raw’. I also have some low current 5v volt devices that need to be connected to the pro-mini, can I use the ‘Vcc’ pin on the board as an output to provide 5v for these devices? (this is what I do on my mega - it seems to work ok on that)

i have read the relevant page, but haven’t found it very clear.


Answerin your two first questions: No. They are internally connected, so you don't have to connect all GND to ground, with only one is OK. The same as VCC pins.

I can't help with your third question, but if you need 5V you an set a Digital pin to HIGH and it will do. Someone will help you better with your third question.

All Gnds are connected. The two on the end for connecting up an FTDI Basic for downloading sketches. Vcc(s) - is output from 5V, 150mA regulator. If you power the board from 12V it will get really warm. If you take 5V off the board from either Vcc it will be hotter still. Vcc can also accept 5V from external source if you don't want to use the regulator.