1.4 Program Memory Write/Erase Requirements
The program Flash memory has a specific write/erase requirement that must be adhered to for proper device operation. The rule is that any given word in memory must not be written without first erasing the page in which it is located. Thus, the easiest way to conform to this rule is to write all the data in a programming block within one write cycle. The programming methods specified in this document comply with this requirement.
Note: A program memory word can be programmed twice before an erase, but only if (a) the
same data are used in both program operations or (b) bits containing
‘
1’ are set to ‘0’, but no ‘0’ is set
to ‘1’. 