UNO

I have completed my first proto board and I am running everything (UNO included) with a 12 Volt supply. NOw what I want to know is can I connect my PC up to the UNO with the 12 V power supply connected? 12 V goes to VIN on Arduino.

Thanks.

ov10fac: I have completed my first proto board and I am running everything (UNO included) with a 12 Volt supply. NOw what I want to know is can I connect my PC up to the UNO with the 12 V power supply connected? 12 V goes to VIN on Arduino.

Thanks.

Schematics?

Plug the USB cable into the USB port like normal - if power is connected via Vin or the barrel jack (not an external 5v supply on the 5v pin) this is the correct way to connect to the Arduino via USB while connected to external power

Disclosure: we occasionally hear of people doing this (and other things involving external power with USB connected that are correct and should be 100% safe) and it trashing the 16u2 on the official uno and faithful clones (I am convinced there is a design flaw relating to the 16u2 and power switching circuit on the Uno, but I don't know what it is). Have not heard similar reports on clones with CH340G or CP2102, just boards with the 16u2, and it's quite rare compared to how frequently people do this without issue.

Many thanks. I appreciate the information.