So i was working on controlling my robot via my arduino 2560 ADK when i think i did some real damage to my board.
The arduino was wired to a motor driver circuit. The motor driver circuit was powering the arduino with 5v. (LM35) + GND. and the motors were powered by a 12V battery.
initially, i did not give the arduino any external power. letting it power from the USB allowed me to control the motor from the serial console. but the motor speed was very slow.
(it was much faster if i simply connected the motor control line to the arduino's 5V supply)
even after powering the arduino from the motor driver circuit, manually touching the control lines to the arduino's power supply worked fine.
when i attached the USB to the arduino. immediately my mac shut down. i panicked and disconnected the entire setup.
now,
a) when i power up the arduino by any means, the RX and TX lines are continuously on.
b) the lines do not blink even if i hold the reset button or manually grounding the reset pin.
b) my mac gives the following error.
USBF: 7412.280 The IOUSBFamily is having trouble enumerating a USB device that has been plugged in. It will keep retrying. (Port 1 of Hub at 0x14000000)
USBF: 7416.640 The IOUSBFamily was not able to enumerate the device (Port 1 of Hub at 0x14000000).
i want to know if the board is damaged beyond recovery or is there anyway that i can fix it?
it was getting it's 5V + GND from the motor circuit. just checked the output of that, it's 5V and coming through a voltage regulator .
the motor circuit however has a 12V battery connected to it to power the motors.
5V. This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
It seems so. If you read that thread I posted, you will see I was about a day from trying the same thing until I read that post.
There is a FET on the board that disconnects the usb power bus from the +5v bus when external power greater than 6.6v is applied to the Vin pin. If there is no voltage applied to Vin, then the buses are connected with power supplied on both buses. Bad news for one of them.
