LCD data
[43210]
.....
|||||_/ 0 \_ main power / off
|||| \ 1 / \ on
||||__/ 0
||| \ 1
|||___/ 0 \____ set to 1 for a certain amount of time to reset ide.
|| \ 1 /
||____/ 0 \_ ide powered / off
| \ 1 / \ on
|_____/ 0 backlight off
\ 1 backlight on
All bits are probably for powering various parts of the board.
P1 has only 5 useful bits
[76543210]
........
||||||||_/ 0 \_ led
||||||| \ 1 /
|||||||__/ 0
|||||| \ 1
||||||___/ 0 \_ LCD
||||| \ 1 /
|||||____/ 0 \_ LCD
|||| \ 1 /
||||_____/ 0
||| \ 1
|||______/ 0 \_ UART Rx
|| \ 1 /
||_______/ 0 \_ UART Tx
| \ 1 /
|________/ 0
\ 1
[76543210]
........
||||||||_/ 0
||||||| \ 1
|||||||__/ 0
|||||| \ 1
||||||___/ 0
||||| \ 1
|||||____/ 0
|||| \ 1
||||_____/ 0 \_ I2C SCL line
||| \ 1 /
|||______/ 0 \_ I2C SDA line
|| \ 1 /
||_______/ 0
| \ 1
|________/ 0
\ 1
[210]
...
|||_/ 0
|| \ 1
||__/ 0
| \ 1
|___/ 0
\ 1
P4 has only 3 useful bits
[76543210]
........
||||||||_/ 0
||||||| \ 1
|||||||__/ 0
|||||| \ 1
||||||______ ADC channel 2
|||||
|||||____/ 0
|||| \ 1
||||_____/ 0 USB not plugged
||| \ 1 USB plugged
|||______/ 0
|| \ 1
||__________ ADC channel 6
|
|___________ ADC channel 7
[76543210]
........
||||||||_/ 0
||||||| \ 1
|||||||__/ 0
|||||| \ 1
||||||___/ 0
||||| \ 1
|||||____/ 0 \_ ide related
|||| \ 1 /
||||_____/ 0 deactivate USB chip
||| \ 1 activate USB chip
|||______/ 0
|| \ 1
||_______/ 0 \_ fiddled with to change usb state
| \ 1 /
|________/ 0
\ 1
[76543210]
........
||||||||_/ 0 'on' button released
||||||| \ 1 'on' button pressed
|||||||__/ 0 battery too low to start (or run)
|||||| \ 1 (battery ok)
||||||___/ 0 \
||||| \ 1 \__ related to CFC detection
|||||____/ 0 /
|||| \ 1 /
||||_____/ 0
||| \ 1
|||______/ 0
|| \ 1
||_______/ 0
| \ 1
|________/ 0 DC is plugged
\ 1 No DC
[3210]
....
||||_/ 0 \_ Keep alive. Flick this bit to maintain power when DC unplugged.
||| \ 1 /
|||__/ 0
|| \ 1
||___/ 0
| \ 1
|____/ 0
\ 1
P8 has only 4 bits.
P9 is used for I2S data transfer (sound)
[76543210]
........
||||||||_/ 0
||||||| \ 1
|||||||__/ 0
|||||| \ 1
||||||___/ 0
||||| \ 1
|||||____/ 0
|||| \ 1
||||_____/ 0
||| \ 1
|||______/ 0 \_ related to smsc chip
|| \ 1 /
||_______/ 0
| \ 1
|________/ 0
\ 1