[SOLVED]Supply with 12 volt into Vin pin and connect USB to computer for control

Other Hardware General Electronics
1

Hi all,
if I want supply the Arduino Duemilanove board via VIN pin and I want occasionally put USB to control the data, how the board works?

When I put the USB cable to the computer and I supply via the POWER CONNECTOR all work fine. The board understand that 2 possible supply are applicated and choiche automatically the best...

But this automaticcally choice has done also suing USB and VIN pin?

Thank very much,
Polpe

2

polpe:
Hi all,
if I want supply the Arduino Duemilanove board via VIN pin and I want occasionally put USB to control the data, how the board works?

Yes it will work fine. The arduino is designed for such situations.

When I put the USB cable to the computer and I supply via the POWER CONNECTOR all work fine. The board understand that 2 possible supply are applicated and choiche automatically the best...

Not a matter of which is best, if voltage is avalible on the Vin pin or from the external DC connector then it will always be selected over the USB power.

But this automaticcally choice has done also suing USB and VIN pin?

Yes, the rule is if both USB and Vin/external power are avalible then the board will use only the Vin/external power.
Lefty
Thank very much,
Polpe

3

Should work fine. See the schematics for the Uno, 2009, etc. They all contain circuitry that detects the presence of (IIRC) a voltage of more than 7V on the Vraw pin and then disconnect the USB bus. So, if you plug a 9V power supply into the power inlet on the Uno board, the 5V power supply from the USB bus should get disconnected.

One way to test this is to look at the power LED on the Arduino board as you plug and unplug an external power supply or the USB cable. As long as one of the two is inserted (and your computer is on) the light should stay on.

4

Thank you,
finally I switch on the circuit and all works fine as you told me.

All the best,

Polpe