AAEON PCM-8120 - Manual (Page 56)

C o m p a c t B o a r d P C M - 8 1 2 0
Appendix A Programming the Watchdog Timer A-3
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.
(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.