Intel NuPRO-850 General Interrupt Status Register, Reload Register, Offset 68H WDT Lock Register

General Interrupt Status Register

This register is at Base + 08H. Bit 0 is set when the first stage of down-counter reaches zero.

Bit 0 = 0 – No Interrupt

Bit 1 = 1 – Interrupt Active

NOTE: This bit is not set in free-running mode.

Reload Register

This register is at Base + 0CH. Write 1 to bit 8 will reload the down-counter’s value. To prevent a timeout:

1.Write 80H to offset BAR + 0CH

2.Write 86H to offset BAR + 0CH

3.Write a ‘1’ to RELOAD[8] of the reload register

Offset 60 – 61H: WDT Configuration Register

Bit 5 indicates whether or not the WDT will toggle the WDT_TOUT# pin when WDT times out. (0 = Enabled, 1 = Disabled)

Bit 2 provides two options for prescaling the main down-counter. (0 = 1ms – 10min, 1 = 1us – 1sec)

Bit [1:0] allows the user to choose the type of interrupt desired when the WDT reached the end of the first stage without being reset. (00 = IRQ, 01 = reserved, 10 = SMI, 11 = Disabled)

NOTE: The WDT does not support SMI now. IRQ uses APIC 1, INT 10 and it is active low, level triggered.

Offset 68H: WDT Lock Register

Bit 2 is used to choose the functionality of the timer. (0 = Watchdog Timer mode, 1 = Free running mode) The free-running mode ignores the first stage and only uses Preload Value 2. In free-running mode it is not necessary to reload the timer as it is done automatically every time the down-counter reaches zero.

Bit 1 enables or disables the WDT. (0 = Disabled, 1 = Enabled)

Bit 0 will lock the values of this register until a hard reset occurs or power is cycled. (0 = unlocked, 1 = locked) The default is Unlocked.

Watchdog Timer • 37