Intel SBC-455 manual Watchdog timer setup, Watchdog timer time-out signal select JP6

Watchdog timer setup

Watchdog timer time-out signal select (JP6)

If CPU processing comes to a halt because of EMI or software bugs, the watchdog timer can either reset the CPU or signal an interrupt on IRQ15.

Watchdog timer time-out signal select (JP6)

Reset CPU(default)				IRQ15
1	2	3	1	2	3

Watchdog timer programming

The watchdog timer must be programmed to write to I/O port address 443 at an interval shorter than the timer's preset interval. The timer's interval has a tolerance of ±5%, so you should pro- gram an instruction that will refresh the timer before a time-out occurs. The following steps illustrate how you might program the watchdog timer.

1.Write to I/O port 443 (Hex) and designate a time-out interval. This will enable the watchdog and set up its time-out interval.

2.Write to I/O port 080 (Hex) and any random value. This will in turn disable the watchdog timer.

28SBC-455 User's Manual