EVOC PPC-1507, Manual

Page: 35 / 81

Chapter 3 Motherboard Installation
PPC­1507 ­ 29 ­
save gpio base address
Out dx, eax ;
Add dx, 4 ;PCI configuration data port
In ax, dx ;read 0cfch to ax
And ax, 0FFF0h ;mask bit0, ax gpio base address saved in ax
xchg dx, ax ;save the base address to dx
;;;2, set the defined functional pin to be gpio
mode
Add dl,30h ;base+offset30h, GPIO Use Select 2 Register
In eax,dx ;get the current register value to eax
Or al, 0ffh ;set the lower 8­bit to be 1 and defined as GPIO
;;bit[8:0] corresponding with gpio[39:32],
;0 = Signal used as native function.
;1 = Signal used as a GPIO.
Out dx
，
al ;write the set value back to the register
;;;set the defined pin to be input output mode
Add dl, 34h ;base+ GPIO Input/Output Select 2 Register
;0 = Signal used as output
;1 = Signal used as input
In eax, dx ;get the current register value to eax
;
Or al, 0fh ;;bit[4:0] set as 1, gpio[35:32] is used as input pin
And al, 0fh ;;bit[8:5] set as 0, gpio[39:36] is used as output pin
Out dx, al ; write the set value back to the register