Undocumented registers

[LaZsolt]

I found few IO registers, which seems to me, are undocumented.

and more undocumented registers:
DIDR2 register at address 0x76,
AC1 trimming register at address 0x5A
AC0 trimming register at address 0x52,

In my opinion:
These registers are designed for use during manufacturing process to quality measure and calibrating.

• OCPUE is a register which somehow can control port E pull-up resistors. I found this register's definition in file lgtx8e.h, next to port E definition.
• LDOCR is could be a register which may control the internal LDO (Low-Dropout Regulator). VSELx bits may select the LDO output voltage, and PDEN bit disable the LDO.