Global American 3307553, Руководство пользователя

Страница: 49 / 53

Appendix C <Watchdog Timer Programming Guide>
(1) General Description
WDT source from : WinBond 83627HF
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
MOV DX,2EH
MOV AL,0F0H
OUT DX,AL
MOV DX,2FH
MOV AL,3CH
; select logical device 1
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 :
49