Persistent data lost after DFU

[peterh]

I use the persistent storage manager for saving some calibration parameters. It seems to work ok - I can power off/on, and the values are still there.

However, after I perform a firmware update, either OTA by using the DFU app or just using jlink all my calibration data are lost. Is this the expected behaviour, or do I need to do something special in order for my data to be persistent, even across firmware updates?

[Stefan Birnir Sverrisson]

Hi peterh

Perhaps the bootloader is overwriting your application data that you store in flash. To prevent that, you need to consider where the bootloader is writing its data and preserve space for application data in bootloader settings, i.e. in the dfu_types.h -> DFU_APP_DATA_RESERVED.

For realizing how the bootloader operates exactly, watch this video.

To realize better how data is placed in flash during bootloader update, look at this thread.

Further bootloader info is given on this thread.

[peterh]

The default bootloader doesn't preserve space for app data, i.e. DFU_APP_DATA_RESERVED = 0. Guess I'll have to build one myself - thanx for the useful pointers to documents etc.