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Dallas 80C320 / DS80C320
Power Failure Interrupt

Power Failure Interrupt

A new interrupt can be enabled which is triggered when the operating voltage drops below Vpfi (see chip spec sheet.) This can be useful to make preparations for a power failure.

WDCON.5 (EPFI) is the enable for the Power Failure Interrupt. When this bit is set, a low operating voltage will trigger the interrupt. When the bit is clear, the interrupt will not be triggered.

WDCON.4 (PFI) is the flag that is set when the power falls below Vpfi. If the interrupt is enabled (via bit EPFI), an interrupt will be triggered when this bit is set. Even if the power failure interrupt is not set, this bit will be set to reflect a low-power status.

Once PFI is set by the hardware, software must clear it manually. The bit will not be cleared automatically.

The interrupt vector for the power failure interrupt is 0033h.

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