AN6091 ('L0->'U0 migration) comments
This is not a discussion on the 'U0 as such (that'd need some time to sink in); just comment on the 'L0->'U0 migration document, AN6091. It's a very detailed and extensive document, and following items are just relatively insignificant minor issues/typos:
- after an optimistic introduction in Pin compatibility chapter (The STM32U0 and STM32L0 series share a high level of pin compatibility.) the subsequent subchapters basically say "nah, forget about it". The TSSOP-20 package is entirely different. On the QFN packages, 'U0 does not have VSS on the exposed pad, so two pins are simply used as VSS, making drop-in impossible. These make the optimistic intro somewhat less substantiated.
- pity that the consumption - which is supposed to be the main selling point of 'U0 - is not presented side-by-side with 'L0, making it hard to compare
- Tab.16 description of reset state of GPIOs is incorrect as 'L0 has Analog as defaults too; instead of 'L0 mentions 'L1 , clearly a fossil (see also below for chapter 6.8)
- Tab.16 when talks about timers, fails to highlight a - IMO very important fact, that contrary to 'L0 which has no 32-bit timers, TIM2 in 'U0 is 32-bit
- Tab.23 incorrectly split "battery backup domain" in the first column
- Tab.24 RTC_TAFCR (L1) -> RTC_TAMPCR etc. is a fossil
- Chapter 6.8 talks about Routing Interface. There's no RI in 'L0, this is some fossil from 'L1
- Chapter 6.11 should've mentioned the different erased state of FLASH (0x00 'L0 vs. 0xFF 'U0), as this is a quite surprising/unexpected thing, and this might be potntial issue when migrating
- Chapter 6.14 says, "Two serial audio interfaces (SAI) replace the I2S interface of the SPI on STM32U0 devices.", yet table 31 for 'U0 says "NA", and there seem to be no SAI mentioned in the 'U0 DS either.
- Tab.35 for 'U0 states 200 mA/Msps consumption; that's certainly too much, should probably be 200uA/Msps
- Tab.37 for 'L0 says "COMP1 fixed threshold", I don't understand what "fixed threshold" is supposed to mean there
- Tab.38 Opamp - there's no opamp in 'L0, yet the "features" row contains them in 'L0, obviously moved inadvertently from the 'U0 column, and there's a funny line in "configuration row" saying that registers are not organized in the same way as in 'L0...
JW
PS. @Lina_DABASINSKAITE , we will need a STM32U0 Series tag ("label") here.