Arduino Uno based on 328p micro-controller board only works while I am inserting the serial cable between the board and the computer and I can control the speed of my two motors and every thing is work properly, but when I eject the serial cable it works badly and there is no control, is that some thing occurs like auto Reset?

There is always 5 volt feeding the Arduino, I get 5 volt regulated from the battery using "5v regulator", this regulated voltage is always connected to the Arduino board.

  • What is powering the arduino when its not connected to the computer? the arduino might be browning out without the usb power.
    – BrettAM
    Sep 13, 2015 at 16:20
  • there is always 5 volt feeds the arduino, i get 5 volt regulated from the battery using "5v regulator", this regulated voltage always connected to the arduino board.
    – omran
    Sep 13, 2015 at 16:39
  • 1
    5V is good, but it's not enough. Power (in this context, current) matters. You mention 2 motors. Those things tend to draw relatively a lot of current. Are you sure that the battery you are using can support the power requirements of the system? Sep 13, 2015 at 18:18
  • @lgor Stoppa my 2 Motors feeding directly from the battery which is 11.30 v, i know that I have just to feeds the arduino by 5v.so no relation between the number of Motors I use.
    – omran
    Sep 13, 2015 at 21:46
  • Yes you can use the 12V battery I have found this in th Arduino Uno specs: Input Voltage (recommended) 7-12V Input Voltage (limit) 6-20V
    – larzz11
    Sep 14, 2015 at 11:38

1 Answer 1


Try increasing the voltage of the power supply. Maybe there might be a problem with the current. The Arduino has a 5V regulator on-board, try using a 9V battery. MAKE SURE THAT YOU CONNECT TO THE DC BARREL CONNECTOR.

Good luck!

  • can I use 12V Battery to Feeds The arduino.
    – omran
    Sep 14, 2015 at 6:02
  • @omran You should be able to.
    – Avamander
    Sep 14, 2015 at 20:22
  • 1
    If you have a problem with current, a 9V battery doesn't supply much (current).
    – Nick Gammon
    Oct 2, 2015 at 4:41

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