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I have a Galaxy Nexus phone which has pogo pins: enter image description here

I have determined which pins are PWR and GND but I don't know what the third pin is. I assume it is for the dock feature of the phone so it knows that it has been inserted into a dock. I'm not sure if I should just apply another 5V to it, put it to ground, or what because I can't find an schematics online for it.

Any ideas?

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Those are not spring loaded, so I'd call those contacts for pogo pins in the dock to mate with, rather than pogo pins themselves. – Chris Stratton Feb 4 '14 at 5:40
up vote 7 down vote accepted

The middle pin is the "sense" pogo pin in the Galaxy Nexus: The phone sends out a 100 millisecond pulse on this pin, then waits for three pulsed responses, to sense what it has been connected to.

From board-tuna-pogo.c:

/* The below constants are in milliseconds */
#define POGO_WAKE_PERIOD                100
#define POGO_ID_PERIOD_TIMEOUT          750
#define POGO_ID_DESKDOCK                50
#define POGO_ID_CARDOCK                 100
#define POGO_ID_CHARGER                 50
#define POGO_ID_USB                     100
#define POGO_ID_AUDIO                   50
#define POGO_ID_NO_AUDIO                100
#define POGO_ID_PERIOD_TOLERANCE        20
#define POGO_DET_DEBOUNCE               80

The three response pulses expected are:

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