I haven't been able to get a commercial BDM working on my board, so I have been modifying a personal BDM I built years ago. In general, I can read and write to the target. However, I notice that after resetting the target, FCLKDIV reads as 0x90. My BDM hasn't set it at that point. Also I can change the value of FCLKDIV with the BDM, although the MSB remains set. It is supposed to be write-once. Any ideas?