Правда? Место в мануале покажете?
User Interface UDP тактируется от MCK.
Документ "6175G–ATARM–22-Nov-06"
Стр. 473, читаем :
WARNING: Due to synchronization between MCK and UDPCK, the software application must wait for the end of the write
operation before executing another write by polling the bits which must be set/cleared.