stm32-rtc-test

In this repo I am trying out STM32's RTC peripheral

Reading Material

• http://embedded-lab.com/blog/stm32s-internal-rtc/ Note: the registers used in this article are not the same as for L4 series.
• Chapter 61: HAL RTC Generic Driver (Page 937 / 2719)

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I'll be playing around with Nucleo L412RB-P

STM32L412RB documents

• STM32L412RB datasheet
• L4xxx reference manual (Details about RTC registers in chapter 34.6 at page 1047/1999)

Important Registers

RTC time register (RTC_TR) Keeps track of hours, minutes, and seconds in BCD format.

RTC date register (RTC_DR) Keeps track of years, week days, months, and date in BCD format.

RTC status register (RTC_SR)

RTC timestamp time register (RTC_TSTR)

Note: The content of this register is valid only when TSF is set to 1 in RTC_SR. It is cleared when TSF bit is reset.

RTC control register (RTC_CR)

RTC status clear register (RTC_SCR)

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Why is BCD format used?

• https://www.youtube.com/watch?v=RDoYo3yOL_E&ab_channel=Computerphile
• https://embedded.fm/blog/2018/6/5/an-introduction-to-bcd
• https://electronics.stackexchange.com/questions/12606/why-do-real-time-clock-chips-use-bcd

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Other notes

• HAL_RTC_GetDate() must be called after HAL_RTC_GetTime() in order for sTime to receive updated values.