Sony AR-B1570 manual Watchdog Timer Setting, Watchdog Timer Trigger, Irq

AR-B1570 User’s Guide

4.3.1 Watchdog Timer Setting

The watchdog timer is a circuit that maybe be used from your program software to detect crash or hang up. The Watchdog timer is automatically disabled after reset. Once you enabled the watchdog timer, your program should trigger the watchdog timer every time before it times out. After you trigger the watchdog timer, the timer will be set to zero and start to count again. If your program fails to trigger the watchdog timer before times out, it will generate a reset pulse to reset the system or trigger the IRQ 9 signal in order to tell your system that the watchdog time is out.

Please refer to the following table in order to properly program Watchdog function

	D7	D6	D5	D4	D3	D2	D1	D0
1	Enable	Reset		Time period
0	Disable	IRQ 9

Users could test watchdog function under ‘Debug’ program as follows:

C:>debug

!O 214 C8H

Generally, watchdog function would reset system after 8 seconds

!O 214 0H

Disable watchdog function

C:>debug

!O 214 88H

Generally, watchdog function would generate IRQ 9 after 8 seconds

!O 214 0H

Disable watchdog function

4.3.2 Watchdog Timer Trigger

After you enable the watchdog timer, your program must write the same factor as triggering to the watchdog timer at least once during every time-out period. You can change the time-out period by writing another timer factor to the watchdog register at any time, and you must trigger the watchdog during every new time-out period in next trigger.

C:>debug

!O 214 CFH

Generally, watchdog function would reset system after 15 seconds

!O 214 40H

Disable watchdog function

Trigger success.

27