I-Bus IBC2602, User Manual

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Chapter 2 - Configuration and Installation
2-6
IBC2602 User's Guide
Watchdog Control
The IBC2602 provides watchdog timer capability using the Dallas
Semiconductor DS1819A reset monitor. The watchdog strobe circuit
consists of a free running clock, which is AND'ed with an enable bit,
which then drives the strobe input of the DS1819A. When the enable bit
is low (x1035h bit 3 is written to 0) the clock will strobe the watchdog.
When this bit is high the clock is shut off and the watchdog timer
activated. Once the watchdog is activated, the enable bit must be taken
back low within 1.12 seconds to reset the timer. Following is a sample
routine for controlling the watchdog timer.
ACTIVATE WATCHDOG
IN
AL,1035h
OR AL,08h
OUT 1035h,AL
STROBE WATCHDOG
IN
AL,1035h
AND AL,F7h
OUT 1035h,AL
OR AL,08h
OUT 1035h,AL
User LED
The IBC2602 contains a user LED on the frontplate. Use the board
specific I/O (see Table 2-5) port 1037h bit 6, to program this LED.
User Input Push Button
A general-purpose push button switch is provided on the IBC2602 front
plate for user configuration. Use the board specific I/O (see Table 2-5)
port 1030h bit 2 to monitor the switch.