COMMELL FS-97A - Manual (Page 49)

FS-97A User’s Manual Watchdog Timer Programming Guide
Watchdog Timer Programming Guide 49
Appendix C
WDT source from : WinBond 83627HF
(1) General Description
Winbond has a WDT feature inside its chip. We implement its
function into our circuit .
There are many configuration Registors ( CR ) in 83627HF. The
following sequence must be followed for CR programming :
(*1) Enter the extended function mode
(*2) Configure the configuration registers
(*3) Exit the extended function mode
EFER : Extended Function Enable Registers.( EFER=2Eh in our system )
EFIR : Extended Function Index Register. ( Same addr. with EFER. )
EFDR : Extended Function Data Register.( Located at addr.[ EFIR +1 ] )
For instance ;
(*1) Enter extended function mode
MOV DX,2EH
MOV AL,87H
CLI ; disable interrupt
OUT DX,AL
JMP $+2
OUT DX,AL
STI ; enable interrupt
(*2) Configurate logical device 1 , configuration register CRF0
MOV DX,2EH
MOV AL,07H
OUT DX,AL
; point to Logical Device Number Register
MOV DX,2FH
MOV AL,01H
OUT DX,AL
; select logical device 1
MOV DX,2EH
MOV AL,0F0H
OUT DX,AL
MOV DX,2FH
MOV AL,3CH
OUT DX,AL ; update CRF0 of LD0 with value 3Ch
(*3) Exit extended function mode
MOV DX,2EH
MOV AL,0AAH
OUT DX,AL
The Configuration Register ( CR ) Definition :