Advantech ITA-460 Series, Руководство пользователя

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ITA-460 User Manual 62
A.1 Programming the Watchdog Timer
The ITA-460’s watchdog timer can be used to monitor the software operations and
take corrective action if the software fails to function within the programmed period.
This section describes the operation of the watchdog timer and procedures for pro -
gramming it.
A.1.1 Watchdog Timer Overview
The watchdog timer is built into the embedded controller and provides the following
user-programmable functions:

It can be enabled and disabled by user program

Timer can be set from 1 to 255 seconds or 1 to 255 minutes

Generates an interrupt or resets signal if the software fails to reset the timer
before time-out
A.1.2 Programming the Watchdog Timer
The I/O port address of the watchdog timer is 2E (hex) and 2F (hex). 2E (hex) is the
address port. 2F (hex) is the data port. You must first assign the address of register
by writing an address value into address port 2E (hex), then write/read data to/from
the assigned register through data port 2F (hex).
Table A.1: Watchdog (Warm Reset) Step by Step
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
Wait IBF clear 0x29A, BIT1, =0
09 Write 0x04 to 0x299 port (Warm) Reset event
Wait IBF clear 0x29A, BIT1, =0
10 Write 0x28 to 0x29A Start watchdog
Wait 1~9 sec
Wait IBF clear 0x29A, BIT1, =0
11 Write 0x29 to 0x29A Stop watchdog
Wait IBF clear 0x29A, BIT1, =0
12 Go to Step 07