Is it OK to supplying a Due with +12 volts at the input socket and plug in a USB cable at the same time?
I'm supplying external circuitry with +12 volts via pin 8 of the Power connector.
I would like to do programming via the USB while +12 volts is supplied through the socket.
Any comments or suggestions are welcome.
Thanks in advance.
MMG
My due has a 2.1mm barrel jack designed to accept 7-20 VDC and I am using a 12V 2A power adapter. This works well, since it's in the middle of the specified range. Why are you using another connector for input? The DUE has circuitry on it that automatically switches between the external barrel jack and the USB programming port (nearest the barrel jack).
I ran my UNO (with Adafruit Datalogging Shield & 2 INA219's) from my 12V (nominal, more like 13-14V) Solar power system for many weeks, connecting USB for serial console occasionally. No problems, even on a closed box in the sun all day.
I have since rigged a 7V adapter on the barrell connector, which works equally well and saves a bit of power.
Compare Due & Uno schematics.
The Due appears to operate with both +12v applied to the power plug and a USB device plugged in at the same time.
The schematic shows +12v (Vin) going to the 5-volt regulator IC2 (LM2734).
+5v feeds into 3.3-volt regulator IC4 (NCP1117) which supplies 3.3v to the Due.
I guess if the 5v reg. is stable enough and can match the 5v from some USB device there is little current hogging and the Due should operate without problem.