AAEON IMBI-Q45 User Manual

Page 37

I n d u s t r i a l M o t h e r b o a r d

I M B I - Q 4 5

Appendix A Programming the Watchdog Timer

A-3

(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 opera-tions
to the Special Address port (2EH). Two different enter keys are
provided to select configuration ports (2Eh/2Fh) of the next step.

Address Port

Data Port

87h, 01h, 55h, 55h:

2Eh

2Fh

(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 W

N/A

Configuration Control

07H 71H R/W 00H WatchDog Timer Control Register
07H 72H R/W 00H WatchDog Timer Configuration Register
07H 73H R/W 00H WatchDog Timer Time-out Value (LSB)

07H 74H R/W 00H WatchDog Timer Time-out Value (MSB)

Configure Control (Index=02h)

This register is write only. Its values are not sticky; that is to say, a
hardware reset will automatically clear the bits, and does not
require the software to clear them.