Aaeon PCM-6897/L Manual page 60

Compact Board
There are three steps to complete 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 during Wait for Key state. To ensure the initial state of
the key-check logic, it is necessary to perform four write operations
to the Special Address port (2EH). Two different enter keys are
provided to select configuration ports (2Eh/2Fh) of the next step.
87h, 01h, 55h, 55h:
(2) Modify the Data of the 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.
WatchDog Timer Configuration Registers
LDN Index R/W Reset Configuration Register or Action
All 02H
07H 71H
07H 72H
07H 73H
Configure Control (Index=02h)
Appendix A Programming the Watchdog Timer
Address Port
2Eh
W N/A Configure Control
R/W 00H WatchDog Timer Control Register
R/W 00H WatchDog Timer Configuration Register
R/W 00H WatchDog Timer Time-out Value
Register
P C M - 6 8 9 7 / L
Data Port
2Fh
A-3