Watchdog Timer Register - Teknor Industrial Computers TEK-AT4LVG Technical Reference Manual

TABLE 7-4: Watchdog Timer Register
ADDRESS
190H, 290H OR 390H:
Bit 0 Read/Write
190H, 290H OR 390H:
Bit 1 Read/Write
The default timeout is 1.6 seconds; however the timeout period can be changed. Shorting
C138 and leaving R152 opened changes the timeout to 100 ms. Shorting R152 and
installing a capacitor at C138 will change the timeout period according to the following
formulae:
Timeout (milliseconds) = (400/47pF) * C
or
C138 = (Timeout (milliseconds) * 47pF) / 400ms.
For instance, an external capacity of 100pF will lengthen the timeout to 851 ms and a
1000pF will bring it to 8.5 seconds.
Installing and Working With System Components
REGISTER
Watchdog enable
Watchdog refresh
7-12