WinSystems PPM-C412, Руководство по эксплуатации продукта, Страница: 23 / 63

PPM-C412/Configuration
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NOTE WinSystems recommends using a long timeout if the watchdog is enabled when trying
to boot any operating system.
Enable, disable, or reset the watchdog by writing the appropriate values to the
configuration registers located at I/O addresses 565h and 566h. Enable the watchdog by
writing a timeout value other than zero to the I/O address 566h and disable it by writing
00h to this I/O address. Service the watchdog timer by writing the desired timeout value
to I/O port 566h. If the watchdog has not been serviced within the allotted time, the
circuit resets the CPU.
Set the timeout value from 1 second to 256 minutes. If port 565h bit 7 equals 0 , the
timeout value written into I/O address 566h is in minutes. The timeout value written to
address 566h is in seconds if port 565 bit 7 equals 1 .
7.9.2 Standard
Enable or disable the watchdog via software by writing an appropriate timeout value to
I/O port 1EEH.
7.9.3 Legacy
The Legacy watchdog timer has a fixed reset interval of 1.5 seconds. Enable the
watchdog by writing 1 or disable it by writing a 0 to I/O port address 1D0.
Table 13: Watchdog timer examples
Port Address Port Bit 7 Value Port Address Value Reset Interval
565H x 566H 00h Disabled
565H 1 566H 03h 3 seconds
565H 1 566H 1Eh 30 seconds
565H 0 566H 04h 4 minutes
565H 0 566H 05h 5 minutes
Table 14: Timeout values
Port Address Value Reset Interval
1EEH 00h Disabled
01h 3
seconds
03h 30 seconds
05h 300 seconds
1EFH Any Reset timer