This is a free running 16-bit up-counter that is clocked at the SYSCLKOUT rate. The counter value is
reset to 0x0000 when a valid interrupt edge is detected and then continues counting until the next valid
interrupt edge is detected. When the interrupt is disabled, the counter stops. The counter is a free-running
counter and wraps around to zero when the max value is reached. The counter is a read only register and
can only be reset to zero by a valid interrupt edge or by reset.