Filter
Top Products
Chapter 3 Software Configuration
Page:3-10
PMB-601LF USER
′
S MANUAL
3-8. WATCHDOG TIMER CONFIGURATION
The I/O port address of the watchdog timer is 2E(hex) and 2F(hex). 2E (hex)
is the address port. 2F(hex) is the data port. User must first assign the
address of register by writing address value into address port 2E(hex), then
write/read data to/from the assigned register through data port 2F (hex).
Configuration Sequence
There are three steps to completing the configuration setup:
(1) Enter the MB PnP Mode.
(2) Modify the data of configuration registers.
(3) Exit the MB PnP Mode.
Undesired result may occur if the MB PnP Mode is not exited normally.
(1) Enter the MB PnP Mode
To enter the MB PnP Mode, four special I/O write operations are to be
performed.
(2) Modify the data of configuration registers
All configuration registers can be accessed after entering the MB PnP Mode.
Before accessing a selected register, the content of index 07h must be
changed to the LDN to which the register belongs, except some Global
registers.
(3) Exit the MB PnP Mode
Set bit 1 of the configure control register (index=02h) to “1” to exit the MB
PnP Mode.
Sample code:
;***********************************************;
; Enter PnP Mode
;***********************************************;
MOV DX,2Eh
MOV AL,87h
OUT DX,AL
MOV AL,01h
OUT DX,AL
MOV AL,55h
OUT DX,AL
MOV AL,55h
OUT DX,AL
;***********************************************;
; Select LDN to 07h
;***********************************************;
MOV DX,2Eh