System Installation
WADE-8044 User’s Manual
3-4
3.4
Clear CMOS Operation
The following table indicates how to enable/disable Clear CMOS Function hardware
circuit by putting jumpers at proper position.
JP9
Function
1-2 Short
Clear CMOS contents
Open
Normal Operation
To correctly operate CMOS Clear function, user must turn off the system, shorted JP9
jumper both of pin 1 and pin 2. To clear CMOS contents, please turn the power back
on and turn it off again for AT system, or press the trigger a few times for ATX
system. Removing the jump from JP9 to open and start the system.
3.5 WDT
Function
The working algorithm of the WDT function can be simply described as a counting
process. The Time-Out Interval can be set through software programming. The
availability of the time-out interval settings by software or hardware varies from
boards to boards.
WADE-8044 allows users control WDT through dynamic software programming. The
WDT starts counting when it is activated. It sends out a signal to system reset or to
non-maskable interrupt (NMI), when time-out interval ends. To prevent the time-out
interval from running out, a re-trigger signal will need to be sent before the counting
reaches its end. This action will restart the counting process. A well-written WDT
program should keep the counting process running under normal condition. WDT
should never generate a system reset or NMI signal unless the system runs into
troubles.
The related Control Registers of WDT are all included in the following sample
program that is written in C language. User can fill a non-zero value into the
Time-out Value
Register to enable/refresh WDT. System will be reset after the
Time-out Value to be counted down to zero. Or user can directly fill a zero value into
Time-out Value Register to disable WDT immediately. To ensure a successful
accessing to the content of desired Control Register, the sequence of following
program codes should be step-by-step run again when each register is accessed.
Additionally, there are maximum 2 seconds of counting tolerance that should be
considered into user’ application program. For more information about WDT, please
refer to Winbond W83627DHG-E data sheet.
There are two PNP I/O port addresses that can be used to configure WDT,
1) 0x2E: EFIR (Extended Function Index Register, for identifying CR index number)
2) 0x2F: EFDR (Extended Function Data Register, for accessing desired CR)
