STM32F0 backup registers are not supported neither by HAL nor by LL drivers. Why is that?

schneider · ‎2020-10-11

In addition neither the datasheet nor the reference manual mention how to access it but the older (pre HAL era) driver versions did support this.

The backup registers are even missing in the RTC register map of the reference manual even though these registers are clearly available on all F0 MCUs.

waclawek.jan · ‎2020-10-11

The 'F0x0 "value line" are physically the same chips as their non-zero-ending counterparts ('F031 in your case), except that some of their features are "not available". In fact, they are usually not disabled in any way, but they are just simply not tested, i.e. not guaranteed to function; and, in future, would ST see enough demand, they may produce a chip which genuinely won't contain those features.

JW

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waclawek.jan · ‎2020-10-11

> The backup registers are even missing in the RTC register map of the reference manual

Not missing in my copy of RM0091:

JW

schneider · ‎2020-10-11

indeed... I did not check all manuals but to be more specific: I am using the stm32f030f4p6 so the reference manual is RM0360 and it is missing there but the code works just fine when accessing the registers before and after a reset the data is persistent.

waclawek.jan · ‎2020-10-11

The 'F0x0 "value line" are physically the same chips as their non-zero-ending counterparts ('F031 in your case), except that some of their features are "not available". In fact, they are usually not disabled in any way, but they are just simply not tested, i.e. not guaranteed to function; and, in future, would ST see enough demand, they may produce a chip which genuinely won't contain those features.

JW

schneider · ‎2020-10-12

Thanks for the confirmation, I was suspecting something like that. Good to know to not count on those features then for a commercial product.