I have two i.MXRT1052 EVK boards and am running the firmware from AN12149. I have the hardware configured just like the app note. The PPS signals are on a scope and the offset is about 65nS and dithering approximately 50nS. I have not edited any of the AN configured constants. So, why do you think the AN12149 has a delta t of about 11nS and mine is a lot larger? What would you recommend adjusting? I'm still learning the finer details of the note but hoped NXP could offer suggestions quicker.