Bits 0:15 - When UNIFY = 0, read the 16-bit counter value at which this register was last captured. When UNIFY = 1, read the lower 16 bits of the 32-bit value at which this register was last captured.
Bits 16:31 - When UNIFY = 0, read the 16-bit counter value at which this register was last captured. When UNIFY = 1, read the upper 16 bits of the 32-bit value at which this register was last captured.