in a software migration project 68HC05X16 to 9S08DZ32 I have to
implement a scheme for 'byte-wise' writes to EEPROM (as it was
possible with HC05, which had 256 byte of EEPROM).
9S08DZ has 1024 bytes of EEPROM with an erase size of 8 bytes
at once. To write to an individual byte I first have to erase 8 bytes
and then restore 7 of them because only 1 byte needs to be changed.
Now my question:
Is it possible to program a (already programmed) byte without a prior
8-byte-erase if I only want to reduce the number of 1-bits in that byte?
(example of what I would like to do: after erase the byte is 0xFF, then I
program it with 0xC3, then I program it with 0x82h, which is a 1->0 transition
for bit 6 and for bit 0)
Data sheet (MC9S08DZ60 Series Rev.4, page 54) says:
"NOTE Before programming a particular byte in Flash or EEPROM,
the sector in which that particular byte resides must be erased
by a mass or sector erase operation"
This looks like the 1-->0 transition requires in all cases a
previous erase operation.
Does anyone have experience with this issue?