Advantech SKY-524, Руководство пользователя

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SKY-524 User Manual 88
The SKY-524’s watchdog timer can be used to monitor system software operation
and take corrective action if the software fails to function within the programmed
period. This section describes the operation of the watchdog timer and how to pro-
gram it.
A.1 Watchdog Timer Overview
The watchdog timer is built in to the EC controller IT8528E. It provides the following
functions for user programming:
 Can be enabled and disabled by user’s program
 Timer can be set from 1 to 255 seconds
 Generates an interrupt or reset signal if the software fails to reset the timer
before time-out
A.2 Programming the Watchdog Timer
The I/O port address of the watchdog timer is as below:
Here is an example to step by step program the Watchdog Timer.
Address Description
0x57 Event - Warm Reset: 0x04
0x5E Warm Reset Timer (High BYTE)
Based 100ms
0x5F Warm Reset Timer (Low BYTE)
Step Action Description
00 Read 0x299 port Clear I/O port
Wait IBF clear 0x29A, BIT1, = 0
01 Write 0x89 to 0x29A
Wait IBF clear 0x29A, BIT1, = 0
02 Write 0x5E to 0x299 port
Wait IBF clear 0x29A, BIT1, = 0
03 Write 0x00 to 0x299 port Set 10 sec (high byte)
Wait IBF clear 0x29A, BIT1, = 0
04 Write 0x89 to 0x29A
Wait IBF clear 0x29A, BIT1, = 0
05 Write 0x5F to 0x299 port
Wait IBF clear 0x29A, BIT1, = 0
06 Write 0x64 to 0x299 port Set 10 sec (low byte)
Wait IBF clear 0x29A, BIT1, = 0
07 Write 0x89 to 0x29A
Wait IBF clear 0x29A, BIT1, = 0