flash max number of writing ?

[Lennart]

Hello !

I have read in DevZone, but still not sure regarding nRF52832 .

For nRF52832 and page size 4k, and regarding only writing zero-bits.

Can I in same page perform total 6144 number of 32-bits writings (6 times each 32-bit address) without erase that 4k page?

Edit: "corrected to 6 times".

Best regards Lennart Vedin for tss.se

[Lennart]

I see I'm not really clear in my question, because most of answers aim "you cannot write 1". I know that's for all flash. And I do not aim writing '1'. But I have read that also writing zero-bits has some kind of limitations for writing-operations, or can I write one single zero-bit each time by 32768 write-operation to fill the 4k with zeros ? 

I aim perform similar as following for a 4k page without erase:

1. Writing a 14-bit value (bit 0 to 13 ) into each 32-bit address, leaving all other 18 bits unmodified.  I.e. 1024 write operations.

2. Writing a 14-bit value (bit 16 to 29 ) into each 32-bit address, leaving all other 18 bits unmodified.  I.e. 1024 write operations.

3. Writing a zero into bit 14 for each 32-bit address leaving all other 31 bits unmodified.  1024 write operations.

4. Writing a zero into bit 15 for each 32-bit address leaving all other 31 bits unmodified.  1024 write operations.

5. Writing a zero into bit 30 for each 32-bit address leaving all other 31 bits unmodified.  1024 write operations.

6. Writing a zero into bit 31 for each 32-bit address leaving all other 31 bits unmodified.  1024 write operations.

In total it is 6144 write-operating, writing one or several zero-bits into the page. (and I correct, it is actually 6 write-operations in each 32-bit address)

I need to have this confirmed by Nordic (e.g. Torbjørn Øvrebekk) , or we might have an issue later (too late).

Best regards Lennart Vedin for tss.se

[awneil]

Again, it's the Erase which causes the wear - not the writing of ones to zeros.

But you can only ever write any one bit from '1' to '0' once - so it is still the same number as the number of erase cycles!

[Lennart]

Ok, but this is not what foks write in this tread https://devzone.nordicsemi.com/f/nordic-q-a/26382/what-is-the-real-nrf52840-max-writes-to-a-flash-block

They write some limitation of total 403 write-operation for the nRF52840 in some context. 

And in Nordic PS document it say " The same block in flash can only be written nWRITE number of times before an erase must be performed using ERASEPAGE or ERASEALL.
"

So what does that mean ?

[awneil]

Ah - what Sigurd  writes there is about losing the stored value, rather than wear of the sells.

So that's a different limitation - but, yes, that does mean that you do also have a limited number of writes between erases.

[Lennart]

Ok I see, it will recover on an erase, but until erase it does not work anymore however.