System Installation
PEB-2737VLA User
’s Manual
3-5
There are two I/O ports as I/O access window for configuring WDT,
1) IO port 0x2E is H/W strapped and named as EFIR (Extended Function Index
Register, for identifying CR index number)
2) IO port 0x2F is H/W strapped and named as EFDR (Extended Function Data
Register, for accessing desired CR)
<< How to access W83627DHG Configuration Register >>
First, it needs to enter extended function mode.
Enter extended function mode for accessing W83627DHG configuration registers:
outportb(EFIR, 0x87);
outportb(EFIR, 0x87); // double IO write
Read Configuration Register CR_rx, and keep this byte to unsigned char al_char
outportb(EFIR, CR_rx ) ;
al_char = inportb(EFDR) ;
Write Configuration Register CR_wx with byte al_char1 ;
outportb(EFIR, CR_wx ) ;
outportb(EFDR, al_char1);
Exit extended mode after completion of configuration register access.
outportb(EFIR, 0xaa);
<< How to access W83627DHG WDT Configuration Register >>
Must enter extended function mode first , then follow the following steps for
accessing WDT registers.
Step(1) : CR2B_bit4P0
Initialize the multiplex pin ( pin89 ) to WDTO function
outportb ( EFIR , 0x2B ) ; // al_char1 : unsigned char
al_char1 = inportb ( EFDR ) & 0xEF ; // CR2B_bit4P0
outportb ( EFIR , 0x2B ) ; // init pin 89 to WDT
outportb ( EFDR , al_char1 ) ;
Step(2) : CR07_P08
Ponit to LD8.
outportb ( EFIR , 0x07 ) ;
outportb ( EFDR , 0x08 ) ;
Step(3) : LD8_CR30_bit0P1
Activate LD8
outportb ( EFIR , 0x30 ) ;
al_char1 = inportb ( EFDR ) | 0x01 ; // CR30_bit0P1
outportb ( EFIR , 0x30 ) ; // Activate LD8
outportb ( EFDR , al_char1 ) ;
