Acnodes FPC 6120 User Manual download pdf (Page 110)

661 Brea Canyon Rd., Suite 3

Walnut, CA 91789

tel: 909.598.7388, fax: 909.598.0218

are subject to change without notice. For latest product information,

please visit Acnodes’ web site at www.acnodes.com.

FPC 6120

12.1” Industrial fanless Panel PC

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 cata-

strophic conditions that cause the CPU to crash. This condition may have occurred by external EMIs 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:

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. When 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.

C. WATCHDOG TIMER

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Acnodes FPC 6120 User Manual Page 110