Chapter 3 Software Configuration
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 ;***********************************************; MOVDX,2Eh
MOVAL,87h
OUTDX,AL
MOVAL,01h
OUTDX,AL
MOVAL,55h
OUTDX,AL
MOVAL,55h
OUTDX,AL
;***********************************************; ;Select LDN to 07h ;***********************************************; MOVDX,2Eh
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