RTC in STM3230F4

Arman Ilmak · ‎2018-03-06

Posted on March 06, 2018 at 19:27

Hello guys.

I wanted to design a PCB with this MCU, but I need RTC in my project.I saw the RTC peripheral in the user manual, but I see no pins named VBAT for when the main power is off.

So what should I do?Doesn't this MCU save the real-time clock while there is no power?

Arman Ilmak · ‎2018-03-06

Posted on March 06, 2018 at 19:30

Sorry, the MCU name I wrote is wrong.!!

I mean stm32f030F4px.

henry.dick · ‎2018-03-06

Posted on March 06, 2018 at 19:58

There are chips where the etc module doesn't have its own power domain. In my view that makes the etc mostly useless.

If you need the etc to run on battery, pick a MCU that can support that.

waclawek.jan · ‎2018-03-06

Posted on March 06, 2018 at 23:56

The 'F030 are deliberately cut-down versions of the 'F0x range, so they don't have the VBAT pin, while they do have the RTC implemented. RTC is powered directly from VDD, see Figure 7. Power supply overview in RM0360 rev.4. That reduces the usability of RTC only for keeping time while full power is on.

JW

waclawek.jan · ‎2018-03-06

Posted on March 06, 2018 at 23:39

dhenry,

don't you write your posts on a system (mobile phone, perhaps) with autocorrection switched on? This is the second post of yours with 'etc' instead of 'RTC'.

Jan

Andrew Neil · ‎2018-03-06

Posted on March 07, 2018 at 00:46

waclawek.jan wrote:

RTC only for keeping time while full power is on.

Although, of course, the rest of the chip can be asleep while the power is on ...

Andrew Neil · ‎2018-03-06

Posted on March 07, 2018 at 00:48

That's the trouble with auto-correct - 'etc' is a perfectly valid 'word' ...

More likely, it was the auto-correct which 'corrected' (sic) 'RTC' to 'etc' ...

Arman Ilmak · ‎2018-03-07

Posted on March 07, 2018 at 19:59

Thank u guys for the answers.

So which MCU would you choose if you were me?

My project is not a very speedy project and I just need 10_14 GPIOs and RTC and you know the price is a priority.

henry.dick · ‎2018-03-07

Posted on March 07, 2018 at 20:15

'

the price is a priority.'

some Taiwanese / chinese 8 bitter + external RTC. cannot beat it no matter how you cut it.