Advantech AIMB-221 manual Watchdog timer overview, Reset/Interrupt selection

The AIMB-221's watchdog timer can be used to monitor system software operation and take corrective action if the software fails to function within the programmed period. This section describes the operation of the watchdog timer and how to pro- gram it.

A.1 Watchdog timer overview

The watchdog timer is built in to the super I/O controller W83627HF. It provides the following functions for user programming:

!Can be enabled and disabled by the user's 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.2 Reset/Interrupt selection

The J2 jumper is used to select reset or interrupt (IRQ) 11 in the event the watchdog timer is tripped. See Chapter 1 for detailed jumper settings.

Note! The interrupt output of the watchdog timer is a low level signal. It will be held low until the watchdog timer is reset.

A.3 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 write an address value into address port 2E (hex), and then write/read data to/from the assigned register through data port 2F (hex).

AIMB-221 User Manual 90