ECW-281B Embedded System
Page 150
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 ECW-281B-945GSE
Страница 16: ......
Страница 17: ...ECW 281B Embedded System Page 1 Chapter 1 1 Introduction ...
Страница 25: ...ECW 281B Embedded System Page 9 Chapter 2 2 Mechanical Description ...
Страница 32: ...ECW 281B Embedded System Page 16 Figure 2 7 Internal Overview ...
Страница 33: ...ECW 281B Embedded System Page 17 Chapter 3 3 System Components ...
Страница 59: ...ECW 281B Embedded System Page 43 Chapter 4 4 Installation ...
Страница 74: ...ECW 281B Embedded System Page 58 Figure 4 15 Power Button ...
Страница 75: ...ECW 281B Embedded System Page 59 5 BIOS Screens Chapter 5 ...
Страница 122: ...ECW 281B Embedded System Page 106 6 Software Drivers Chapter 6 ...
Страница 141: ...ECW 281B Embedded System Page 125 Figure 6 24 AC 97 Driver Installation Complete Step 13 The system reboots Step 0 ...
Страница 142: ...ECW 281B Embedded System Page 126 Chapter 7 7 Troubleshooting and Maintenance ...
Страница 148: ...ECW 281B Embedded System Page 132 A Safety Precautions Appendix A ...
Страница 152: ...ECW 281B Embedded System Page 136 B IEI Embedded System Series Appendix B ...
Страница 161: ...ECW 281B Embedded System Page 145 C BIOS Menu Options Appendix C ...
Страница 165: ...ECW 281B Embedded System Page 149 D Watchdog Timer Appendix D ...