NVM write operations are controlled by selecting the desired action with the
NVMCMD bits then starting the operation by executing the unlock sequence. NVM read
operations are started by simply setting the
GO bit after setting the read operation. Available NVM
operations are shown in the following table.
Table 1. NVM Operations
| NVMCMD |
Unlock |
Operation |
DFM |
PFM |
Source/Destination |
WRERR |
INT |
000 |
No |
Read |
byte |
word |
NVM to NVMDAT |
No |
No |
001 |
No |
Read and Post Increment |
byte |
word |
NVM to NVMDAT |
No |
No |
010 |
No |
Read Page |
— |
page |
NVM to Buffer RAM |
No |
No |
011 |
Yes |
Write |
byte |
word |
NVMDAT to NVM |
Yes |
Yes |
100 |
Yes |
Write and Post Increment |
byte |
word |
NVMDAT to NVM |
Yes |
Yes |
101 |
Yes |
Write Page |
— |
page |
Buffer RAM to NVM |
Yes |
Yes |
110 |
Yes |
Erase Page |
— |
page |
n/a |
Yes |
Yes |
111 |
No |
Reserved (No Operation) |
— |
— |
— |
No |
No |
Important: Write operations
are inhibited on all NVM registers while the GO bit is set. The GO bit is cleared by
hardware when the operation is complete. The GO bit cannot be cleared by
software.