Nrf52 flash programming : 'writes in a block between erase'

[Mahendra Tailor]

In the nrf52 OPS datasheet, for NVM and flash programming electrical specification (page 41) it has "Amount of writes in a block between erase" and Minimum for that is 181.

What does that actually mean?

For example, I know and understand "Write/erase cycles", but this is a new one on me.

A sector in nrf52 has 4K which means 1024 dwords. Which means I could end up having 1024 write operations before it is full. So the 181 specified can't be referring to how many times I could write.

To make matters worse, there are 32 bits in a write operation, so there are 32768 bits. So I could theretically have 32 seperate write operations at each of the 1024 locations, giving me a total of 32768 write operation before I would have to erase the block.

I am confused !!

Hope someone can clarify.

[RK]

Section 10.1 "The same block address in the NVM can only be written nWRITE number of times before an erase must be performed using PAGEERASE , ERASEUICR, or ERASEALL."

nWrite is a minimum of 181. So you can write any address in the page 181 times at a minimum before you have to erase the page. Not that that would be very useful as you can only change it a maximum of 32 times before you have all bits set to zero.

I assume the 181 times includes times you write it but don't actually change anything, else it really would be meaningless.

Basically not much of a restriction.

[RK]

yeah I have one of those too - I keep state in a 32 bit word and drop a bit each time I move from one state to another, it's very useful. That lets me mark blocks as allocated, then in-use, then dropped etc, kind of like a filesystem.