Hello~AZ [Renesas] team
i tried to use data flash in a different way than normal sequence.if the flash is individually written on a cell-by-cell basis, it is expected that it will be possible to write up to 8 times on a single byte with one erase.Up to the 2nd write test, it seemed to work, but I saw a cell other than the cell written in the 3rd write test being flipped.
Below is the result of my test.
after erase 0xFF(h) -> 111111111(b) -> read value : 0xFF-> first write 0xFE(h) -> 111111110(b) -> read value : 0xFE-> 2nd write 0xFC(h) -> 111111100(b) -> read value : 0xFC-> 3nd write 0xF8(h) -> 111111000(b) -> read value : 0xFA
I know that "erase -> write" is a normal write cycle, but I tested it out of curiosity, so if you know anything about it, I would appreciate it if you could share it.
thanks
The minimum write unit is 1-byte for the RL78 data-flash, per the specification.
Hello JimB
I already know that the data flash write unit is specified in the specification as 1 byte. The test written in the text was done out of personal curiosity.I was curious about the physical operation because some operations operated as if they were written on a cell-by-cell basis. This is because even some cells can be used in various ways if it was written per cell.
thanks a lot
What you are trying to do may leed into damaging the flash cells. I am not sure how you are doing what you describe in the text but when you try to write the data flash, this access unit will be 1-byte whatsoever.
I understand. Thank you for your kind reply.
Usually, the value of the area that has been written once does not change when attempting to write again, but in the case of rl78f24 data flash, the value changes regardless of the 2nd write (erase -> write -> write).That's why I wondered if it would be written on a cell-by-cell basis.Anyway, thank you for your reply.