EVOC CPC-1817CLD5NA, User Manual

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Appendix
- 44 - CPC-1817CLD5NA
Appendix
Watchdog Programming Guide
The board provides a programmable watchdog timer (WDT) up to 255 levels and
timed by minute or second. Watchdog timeout event can be programmed to reset
system or generate maskable interrupts.
The available IRQ numbers for this board are: 3, 4, 5, 7, 9, 10 and 11.
The following describes WDT program in C language. The steps to program WDT are
listed as follows:
 Enter WDT programming mode;
 Set WDT operating mode, enable WDT/disable WDT.
(1) Enter WDT Programming Mode
/*
Description: the function, PreInitWDT, is used to initialize the registers relevant
to WDT; please invoke the function before configuring and using WDT.
Input: none
Output: none
Note: the function will modify the value of the variable pm_base, which will be
quoted by the function SetWDT.
*/
#define INDEX_PORT 0x4E
#define DATA_PORT 0x4F
unsigned int tmp_reg;
unsigned int pm_base;
VOID PreInitWDT()
{
outportb(INDEX_PORT, 0x55);
outportb(INDEX_PORT, 0x07);