Hi all, just a quick question regarding the Breakout GS.

I'm using the Breakout for a little project and already have 12V power supply, so I thought I'd use a DC-DC converter and get the necesary 5V from there.

Looking through the schematics for the Breakout GS, I've come across http://pubs.gumstix.org/boards/BREAKOUT/GS/PCB00011-R901/B00011.JACK.png that seems to indicate that V_BATT would be where I should connect one of the terminals of the power supply.

So the questions would be:

1) Where should I connect my GND?  I'm planning of using of the the serial ports GND, but that doesn't seem to be the best place for it.  Is there a pin (like V_BATT) that's intended for this use?

2) What's J_GND for?  GND for JTAG?