Advantech ASMB-976 Series, Руководство пользователя

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ASMB-976 User Manual 104
A.1 Watchdog Timer Overview
The ASMB-925 Series watchdog timer can be used to monitor system software oper
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ation 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
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gram it.The watchdog timer is built in to the EC controller IT8528E. It provides the fol
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lowing functions for user programming:

Can be enabled and disabled by user program
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Timer can be set from 1 to 255 seconds
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Generates an interrupt or resets 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
08 Write 0x57 to 0x299 port Watchdog Event