[Solved] Freaduino Mega2560: USB and External Power Supply

Hi, i’m new to arduino (and electronic in general). I read that it’s possible (on Arduino) to use external power (with the jack) and the usb at the same time, but i couldn’t find if on Freaduino Mega2560 is. The wiki says:

"The Arduino can be powered via the USB connection or with an external power supply. The power source is selected automatically.

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board’s power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector.

The board can operate on an external supply of 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts."

It does not specify if i can plug both usb and external power at the same time.

I hope you can help me.


You can plug One @ time. I tried both plugged once.

Yes its better to use one power source @ once. I have worked 5v But i didn't get problem such.i have interfaced 7805 regulator output to 5v input pin.

I have not got any problem with 5v operation.

Its unsafe when you trying to control motor action using same power source to control motor & arduino board, with USB connected.

I’m connecting an efcom gsm shield SIM900 to the Freaduino Mega2560, that’s why i need external power source (9v). I don’t know if this matters, that’s why i tell you.

So it’s not recommended, but suppose i really need to connect it for debugging purposses, will i damage the board or the shield?

Thanks for your quick reply!! ;D

Usually it don’t damage. Even you can use external usb TTL converter( If you still think its unsafe).