The NVMADR value determines which NVM address space is accessed. The
User IDs and Configuration areas allow read and write access, whereas Device and Revision
IDs are limited to read-only.
Reading and writing User ID space is identical to reading and writing PFM space as
described in the preceding paragraphs.
Writing to the Configuration bits is performed in the same
manner as writing to the Data Flash Memory (DFM). Configuration settings are modified one
byte at a time with the NVM Read and Write operations. When a Write operation is performed
on a Configuration byte, an erase byte is performed automatically before the new byte is
written. Any code protection settings that are not enabled will remain not enabled after
the Write operation, unless the new values enable them. However, any code protection
settings that are enabled cannot be disabled by a self-write of the configuration space.
The user can modify the configuration space by the following steps:
- 1.Read the target Configuration byte by
setting the NVMADR with the target address.
- 2.Retrieve the Configuration byte with
the Read operation (NVMCMD =
‘b000).
- 3.Modify the Configuration byte in
NVMDAT register.
- 4.Write the NVMDAT register to the
Configuration byte using the Write operation (NVMCMD =
‘b011) and
unlock sequence.