I want to command a dc motor with android via arduino adk. I succeeded turning on a Led with android but when i change the code i only need to add a new pin so when i define its mode as output the phone doesn't connect with my arduino board !! like the code doesn't accept more than one pin as output !!! Knowing that i'm supplying my board with PC not a supply battery and if i skip the PIN's connexions the phone connects to the board IS IT A Current POWER ? do i need a battery for the board ?