Have to Reset Arduino Uno when using Vin pin

Projects General Guidance
1

Hi,

I'm using an Arduino Uno. I have written some code that definitely works perfectly when powering it from USB or the 12V DC input. However when I power it using the Vin pin in the power section of the board I have to press the hard reset button before the software will run. The green power light comes on, the software just doesn't run.

I am providing 12V to the Vin pin from exactly the same PSU that I use when plugging into the DC input. I can't use the DC input because of the way it is mounted in the box, so need to use Vin.

Any ideas why it should work fine with USB and DC in, but not the Vin pin?

Paul

2

When you used the Vin, were you powering the arduino with other sources such as USB and the power barrel at the same time?

From the schematic, the Vin doesn't go through the diode D7 as the power barrel does. I don't find any other differences.

Have you tried a 9V battery on Vin?