Advantech ITA-2231 Series User Manual

Also see for ITA-2231 Series: Startup manual

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Advantech ITA-2231 Series User Manual Manual pdf 84 page image

ITA-2231 User Manual 72A.1 Programming the Watchdog TimerThe ITA-2231's watchdog timer can be used to monitor system software operationand take corrective action if the software fails to function within the programmedperiod. This section describes the operation of the watchdog timer and how to pro-gram it.A.1.1 Watchdog Timer OverviewThe watchdog timer is built into the super I/O controller SMSC SCH3114. It providesthe following user-programmable functions: Can be enabled or disabled via 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 timerbefore time-outA.1.2 Programming the Watchdog TimerThe I/O port address of the watchdog timer is 680h (hex).Table A.1: Watchdog Timer RegistersAddress: 680h (hex)Register Shift Read/Write Description65 (hex) writeSet seconds or minutes as units for the timer.Write 0 to bit 7: set second as counting unit. [default]Write 1 to bit 7: set minutes as counting unit.66 (hex) write0: Stop timer [default]01~FF (hex): The amount of the count, in seconds or min-utes, depends on the value set in register 65 (hex). Thisnumber decides how long the watchdog timer waits forstrobe before generating an interrupt or reset signal. Writinga new value to this register can reset the timer to count withthe new value.67 (hex) read/writeConfigure watchdog timerBit 1:Write 1 to enable keyboard to reset the timer, 0 to dis-able. [default]Bit 2: Write 1 to enable mouse to reset the timer, 0 to dis-able.[default]Bit 7~4: Set the interrupt mapping of watchdog timer:1111=IRQ15……0011=IRQ30010=IRQ20001=IRQ10000=Disable [default]68 (hex) read/writeControl watchdog timerBit0: Read watchdog state; 1=Timer timeoutBit2: Write 1 to immediately generate timeout signal, andautomatically return to 0 (Write only).Bit3: Writer 1 to allow triggering of timer timeout when P20is effective, 0 to disable. [default]

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