AAEON PCM-5895 Rev.B - Manual (Page 60)

C o m p a c t B o a r d P C M - 5 8 9 5 R e v . B
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)
Register
07H 74H R/W 00H WatchDog Timer Time-out Value (MSB)
Register
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.
Bit Description
7-2 Reserved