MSP430 FLASH/INFOMEM wear leveling possibility

Flash memory areas used to store boot loaders, operating system images, or other executable code, are generally erased less frequently. These areas are considered static.¹

In the MSP430, things like your vector tables are in fixed locations, and thus can't be wear-leveled. In addition, the vector table is usually part of your application code, so that further restricts any effort to wear-level your code segments. I find it unreasonable to expect that you would be reprogramming your code region often enough to come anywhere near the Flash erase/write cycle limits.

Areas used to store data, like info partitions, are generally erased more frequently. These areas are considered dynamic. Dynamic wear-leveling solutions will only distribute flash usage across the data partition.¹

In the MSP430, if you are storing dynamic data in sections of the FLASH (Info or otherwise) you might do some analysis to decide if wear-leveling is necessary. There isn't anything built in, so you would have to implement your algorithm on your own (or find suitable pre-existing code).

I need to periodically save data only (not application code), and hence wished to use INFOMEM for wear-leveling. So the code region would not be erased and reprogrammed. But the MSP spec says flash endurance is minimum 10000 cycles.

MSP datasheet isn't specific whether that means the total number of all writes to flash can't exceed 10000 (in which case wear-leveling won't be of much help to me) or whether each INFOMEM/flash segment can be written up to 10000 times per segment. I need clarification on this issue. Thank you.

>Each mass erase as well as each individual segment erase counts.

I'd appreciate an expansion of the statement "Each mass erase as well as each individual segment erase counts." I'm unsure whether the statement means (a) flash write access will only fail for segments that are each erased/written 10000 times per segment (assuming each segment can withstand 10000 erase cycles of its own) or (b) flash write access will fail for all 20 segments that are each erased+written 500 times per segment (total erase cycles 10000). Please provide a clarification. Thank you.

Thank you for the clarification and advice.

- A.G.

Basically, each individual bit cell has its own ‘erase endurance’, but since you can only erase a whole segment at once, each segment has its own 'age counter'. So my statement meant “each erase, whether segment of mass erase, applied to an individual flash cell, counts”
Flash wear-out happens because electrons are trapped in the isolating area that separates the charge trap (that holds the cell value) form the read/write electronic. At a certain point, these trapped electrons affect the reading of the cell content more than the content of the charge trap, and the cell content can’t be read anymore. So the effect is less, if you didn’t write a ‘0’ to the cell before next erasure. One could say that only cells containing a ‘0’ are really erased during an erase. So the minimum endurance value is a simplified worst-case value. Typically, you can do ten times more write/erase cycles befor efailure, but that's not guaranteed..