NANO-PV-D4252/N4552/D5252 EPIC SBC
Page 129
NOTE:
The following discussion applies to DOS environment. IEI support is
contacted or the IEI website visited for specific drivers for more
sophisticated operating systems, e.g., Windows and Linux.
The Watchdog Timer is provided to ensure that standalone systems can always recover
from catastrophic conditions that cause the CPU to crash. This condition may have
occurred by external EMI or a software bug. When the CPU stops working correctly,
Watchdog Timer either performs a hardware reset (cold boot) or a Non-Maskable Interrupt
(NMI) to bring the system back to a known state.
A BIOS function call (INT 15H) is used to control the Watchdog Timer:
INT 15H:
AH – 6FH Sub-function:
AL – 2:
Sets the Watchdog Timer’s period.
BL:
Time-out value (Its unit-second is dependent on the item “Watchdog
Timer unit select” in CMOS setup).
Table D-1: AH-6FH Sub-function
Call sub-function 2 to set the time-out period of Watchdog Timer first. If the time-out value
is not zero, the Watchdog Timer starts counting down. While the timer value reaches zero,
the system resets. To ensure that this reset condition does not occur, calling sub-function
2 must periodically refresh the Watchdog Timer. However, the Watchdog timer is disabled
if the time-out value is set to zero.
A tolerance of at least 10% must be maintained to avoid unknown routines within the
operating system (DOS), such as disk I/O that can be very time-consuming.
Содержание NANO-PV-D4252
Страница 14: ...NANO PV D4252 N4552 D5252 EPIC SBC Page xiv ...
Страница 15: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 1 Chapter 1 1 Introduction ...
Страница 22: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 8 2 Unpacking Chapter 2 ...
Страница 26: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 12 3 Connectors Chapter 3 ...
Страница 54: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 40 4 Installation Chapter 4 ...
Страница 83: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 69 5 BIOS Screens Chapter 5 ...
Страница 115: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 101 Appendix B B One Key Recovery ...
Страница 121: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 107 Figure B 3 Partition Creation Commands ...
Страница 138: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 124 Appendix C C Terminology ...
Страница 142: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 128 Appendix D D Watchdog Timer ...
Страница 145: ...NANO PV D4252 N4552 D5252 EPIC SBC Page 131 Appendix E E Hazardous Materials Disclosure ...