Refer to the PDF data sheet for device specific package drawings
7.7.3.1 Features
Takes two different clock sources as input to two independent counter blocks.
One of the clock sources is the known-good, or reference clock; the second clock source is the "clock under test."
Each counter block is programmable with initial, or seed values.
The counter blocks start counting down from their seed values at the same time; a mismatch from the expected frequency for the clock under test generates an error signal which is used to interrupt the CPU.