Re: [Gumstix-users] Gumstix, Robostix, and Serial Communication

[Dave H. <dhy...@gm...>]

Hi Dustin,

On Sat, Aug 15, 2009 at 12:37 PM, Dustin Webb<dus...@ya...> wrote:
> Hi Dave:
>
>> You should be able to. The barrel jack switches the GND signal. So the
>> GND from the BOARD connector goes through the barrel jack. When a plug
>> is inserted, then the ground from BOARD is disconnected from the board
>> GND.
>
>> When you remove the jack, it should connect the BOARD GND through to
>> the robostix GND. You should be able to test this with a multimeter.
>> It's possible that your jack isn't working properly.
>
>> If it turns out that your jack isn't working, you could solder a wire
>> from pin 1 to pin 2 (the two pins on the sides. This should make the
>> BOARD connector work properly.
>
> I'm just getting back to this issue. I have to admit I don't completely
> follow what you are saying. However I took my multimeter to the board anyway
> to gain a better understanding of what's going on. What I found is that
> there are 3 terminals on the barrel itself. Two on the sides which appear to
> be connected when the plug is not inserted and disconnected otherwise. Both
> of these terminals are attached to the ground terminal on the BOARD and
> MOTOR headers when the plug is not inserted. When the plug is inserted the
> left terminal is connected to the ground terminal on the BOARD header while
> the right terminal is connected to the ground terminal on the MOTOR header.
> The terminal on the barrel connector, the one coming out from the back, is
> connected to the +5V on both the BOARD and MOTOR headers regardless of
> whether the plug has been inserted.

So that all sounds correct.

> Ultimately I want to power the board from a 5 cell 6V NiMH. Hi have tried
> connecting power to the BOARD and MOTOR headers, though not simultaneously
> because I didn't think that would be beneficial. From that I have found that
> if I don't have the Verdex attached then I can power the Robostix via the
> MOTOR header. If I do have the Verdex attached then I am unable to power
> either the Robostix or the Verdex through either connector. With all that
> said could you help me understand how to achieve my goal?

Make sure your batteries are fully charged, and that you have minus
connected to ground and plus connected to BOARD +5.

Other than that it should work.

The only other thing to try is to connect your battery between +5 on
the BOARD connector and GND someplace else. It might be that the
barrel jack is not getting a good ground though between the BOARD
connector and GND.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/