ST STM32L0x3 User Manual

RM0367 Rev 7 165/1043
RM0367 Power control (PWR)
172
The RTC provides a programmable time base for waking up from Stop or Standby mode at
regular intervals. For this purpose, two of the three alternative RTC clock sources can be
selected by programming the RTCSEL[1:0] bits in the RCC_CSR register (see
Section 7.3.21):
• Low-power 32.768 kHz external crystal oscillator (LSE OSC).
This clock source provides a precise time base with very low-power consumption (less
than 1 µA added consumption in typical conditions)
• Low-power internal RC oscillator (LSI RC)
This clock source has the advantage of saving the cost of the 32.768 kHz crystal. This
internal RC Oscillator is designed to use minimum power consumption.
RTC auto-wakeup (AWU) from the Stop mode
• To wake up from the Stop mode with an RTC alarm event, it is necessary to:
a) Configure the EXTI Line 17 to be sensitive to rising edges (Interrupt or Event
modes)
b) Enable the RTC Alarm interrupt in the RTC_CR register
c) Configure the RTC to generate the RTC alarm
• To wake up from the Stop mode with an RTC Tamper or time stamp event, it is
necessary to:
a) Configure the EXTI Line 19 to be sensitive to rising edges (Interrupt or Event
modes)
b) Enable the RTC TimeStamp Interrupt in the RTC_CR register or the RTC Tamper
Interrupt in the RTC_TCR register
c) Configure the RTC to detect the tamper or time stamp event
• To wake up from the Stop mode with an RTC Wakeup event, it is necessary to:
a) Configure the EXTI Line 20 to be sensitive to rising edges (Interrupt or Event
modes)
b) Enable the RTC Wakeup Interrupt in the RTC_CR register
c) Configure the RTC to generate the RTC Wakeup event
RTC auto-wakeup (AWU) from the Standby mode
• To wake up from the Standby mode with an RTC alarm event, it is necessary to:
a) Enable the RTC Alarm interrupt in the RTC_CR register
b) Configure the RTC to generate the RTC alarm
• To wake up from the Stop mode with an RTC Tamper or time stamp event, it is
necessary to:
a) Enable the RTC TimeStamp Interrupt in the RTC_CR register or the RTC Tamper
Interrupt in the RTC_TCR register
b) Configure the RTC to detect the tamper or time stamp event
• To wake up from the Stop mode with an RTC Wakeup event, it is necessary to:
a) Enable the RTC Wakeup Interrupt in the RTC_CR register
b) Configure the RTC to generate the RTC Wakeup event

ST STM32L0x3 Specifications

General

Brand	ST
Model	STM32L0x3
Category	Microcontrollers
Language	English