F u l | S B C - 7 8 0 |
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Programming
An onboard watchdog timer reduces the chance of disruptions which CPLD (Compact Programmable Logical Device) interface can cause. This
is an invaluable | protective device for standalone or punma | nned |
applications. When the watchdog timer activates (CPU processing has |
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come to a halt), it can reset the system, or generate an interrupt on IRQ10, IRQ11, IRQ15, and NM1. This can be set via I/O Port 444, the function as following:
0:RESET
1:NM1
2:IRQ10
3:IRQ11
4:IRQ15
If you decide to program the watchdog timer, you must write data to I/O port 443 (hex). The output data is a value timer. You can write form 01 (hex) to FF (hex) while simultaneously setting it. When you want to disable the watchdog timer, your program should read a Hex value from I/O port 80 (hex).
The following procesude is a sample program for the watchdog timer:
Type C:\DOS\Debug <ENTER>
To start watchdog timer and set function “Reset” type; o 444 0<Enter>; out 444h data 0
To input Watchdog timers
To disable the watch timer type;i80 <Enter>
The time interval data of the watchdog timer is shown in binary code (8 bits).
Sample 2: 5 seconds
0
0
0
0
0
1
0
1
Appendix A Programming the Watchdog Timer |