GPIOs

From Sp305x wiki

GPIO mapping for DX SKU 21968

GPIO A

bit 0 - tied to Vcc?
bit 1 - power enable? (probably need to set this high to keep the thing turned on after battery power on)
bit 4 - BTN row 1
bit 5 - BTN row 2
bit 6 - BTN row 3
bit 8 - BTN column 1
bit 9 - BTN column 2
bit 10 - BTN column 3
bit 11 - BTN column 4

drive rows, read columns.

Keyboard matrix:

    COL| 1  2  3  4
ROW BIT| 8  9  10 11
-------+--------------
 1   4 | U  D  L  R
 2   5 | B  Y  A  X
 3   6 |ESC OK 

GPIO B

bit 3 - backlight (act. high)
bit 4 - POWER button (act. high)
bit 5 - Headphone detect (act. low)
bit 6 - speaker mute/enable (act. unknown)
bit 8 - LOCK switch (act. high)