EBC-C413/Configuration
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Page 21
Watchdog Timer Examples
7.6
Real-Time Clock/Calendar
A real-time clock (RTC) is used as the AT-compatible clock/calendar. The
RTC supports a number of features, including periodic and alarm interrupt
capabilities. In addition to the time and date keeping functions, the system
configuration is kept in CMOS RAM contained within the clock section. A
battery must be connected for the real-time clock to retain time and date
during a power down.
7.7
Buzzer
The BIOS activates the buzzer during a POST failure. The beep code is
specific to each type of error. Refer to “Power-on Self-Test (POST) Codes”
on page 77 for details.
7.8
Activity Light
The system includes a programmable green activity LED on the board. To
control it, write to I/O address 0x29Dh. Write a 0x01h to turn it on; write a
0x00h to turn it off. See “LED4 User LED” on page 54.
7.9
Clear CMOS Settings Jumper
This jumper can be used to reset the BIOS CMOS settings to the factory
default settings. This jumper ties a specific pin on the FPGA to ground. The
BIOS reads this pin during system startup and if grounded, forces the
settings reset. See “JPBAT - RTC Battery Enable” on page 53.
Port
Address
Port Bit 7
Value
Port
Address
Value
Reset Interval
565h
x
566h
00h
DISABLED
1
01h
1 second (minimum)
1
03h
3 seconds
1
1Eh
30 seconds
1
3Ch
60 seconds
0
01h
1 minute
0
04h
4 minutes
0
05h
5 minutes
0
FFh
255 minutes (maximum)
To reset the watchdog timer, rewrite the timeout value to PORT 566h.
