STM32F030 RTC - What happened to the Periodic Wakeup?

[Andrew Neil]

The original (Rev 1) datasheet said that STM32F030x4, x6, and x8 all had the Periodic Wakeup:

The current (Rev 5) datasheet, which adds the xC variant, now says that only the xC has the Periodic Wakeup:

So what happened?

How/why did it disappear from the x4, x6, and x8 variants?

I don't see anything in the Errata.

The current Reference Manual also says it's only available on the xC:

[KDJEM.1]

Hello @Andrew Neil ,

According to RM0360, the periodic wake-up RTC feature isn't supported in STM32F030x4, STM32F030x6, STM32F030x8 and it is supported only in STM32F070xB, STM32F030xC. 

This misalignment was highlighted internally in STM32F030x8 datasheet rev 3 and was fixed since rev 4.

Thank you.

Kaouthar

[waclawek.jan]

The 'F030 is in fact "value" variant of 3 different 'F0 models ('F031, 'F051 and 'F091; as 'F030 they differ in FLASH size); and the RTC is different in these:

(A historical note: the first 'F0 model was 'F051 and there was also a 'F050 introduced as its "value" variant. That was quickly renumbered to 'F030, when other 'F0 were introduced and their "value" variants were numbered 'F030 too. That's some marketing for you. That process probably had impact on quality of RM0360, too.)

JW

[Andrew Neil]

@KDJEM.1 that doesn't really answer the question!

The Rev 1 datasheet says that STM32F030x4/x6/x8 do have the Periodic Wakeup - how did they get that wrong?

At that time, there was no xC (let alone xB) version mentioned, so it wasn't just a "misalignment" - it was 100% incorrect?

[Andrew Neil]

So probably a copy & paste error?

[waclawek.jan]

I don't know what's the genesis of this particular detail of RTC (consequently the DS). Chapters for individual modules are obviously widely copypasted, we've seen errors stemming from this in the past elsewhere, too.

I wasn't aware there is such thing as missing Periodic Wakeup in RTC2, and I am not aware of any other STM32 model where the Periodic Wakeup would be missing. Not even AN4759 mentions this, and that AN goes to surprising details of the various incarnations of RTC2 and RTC3.

To me, it does not make much sense to omit that, it appears to be a relatively small circuit with immense benefit. But then, who am I to judge this.

I just wanted to point out that the 'F030 is not one part and one has to be very careful when migrating between them.

JW