MSI MS-9A84, Manual, Page: 49 / 49

A-3
WDT Programming MS-9A84
Watchdog Timer
1. Watchdog Timer – WDT
The base address (WDT_BASE) of WDT configuration registers is 0xA10.
1.1 Set WDT Time Unit
val = Inportb (WDT_BASE + 0x05); // Read current WDT setting
val = val | 0x08; // minute mode. val = val & 0xF7 if second mode
Outportb (WDT_BASE + 0x05, val); // Write back WDT setting
1.2 Set WDT Time
Outportb (WDT_BASE + 0x06, Time ); // Write WDT time, value 1 to 255.
1.3 Enable WDT
val = Inportb (WDT_BASE + 0x0A); // Read current WDT_PME setting
val = val | 0x01; // Enable WDT OUT: WDOUT_EN (bit 0) set to 1.
Outportb (WDT_BASE + 0x0A, val); // Write back WDT setting.
val = Inportb (WDT_BASE + 0x05); // Read current WDT setting
val = val | 0x20; // Enable WDT by set WD_EN (bit 5) to 1.
Outportb (WDT_BASE + 0x05, val); // Write back WDT setting.
1.4 Disable WDT
val = Inportb (WDT_BASE + 0x05); // Read current WDT setting
val = val & 0xDF; // Disable WDT by set WD_EN (bit 5) to 0.
Outportb (WDT_BASE + 0x05, val); // Write back WDT setting.
1.5 Check WDT Reset Flag
If the system has been reset by WDT function, this flag will set to 1.
val = Inportb (WDT_BASE + 0x05); // Read current WDT setting.
val = val & 0x40; // Check WDTMOUT_STS (bit 6).
if (val) printf (“timeout event occurred”);
else printf (“timeout event not occurred”);
1.6 Clear WDT Reset Flag
val = Inportb (WDT_BASE + 0x05); // Read current WDT setting
val = val | 0x40; // Set 1 to WDTMOUT_STS (bit 6);
Outportb (WDT_BASE + 0x05, val); // Write back WDT setting