AN3404

Low power modes

Doc ID 018847 Rev 3

13/30

4.6.2

Exiting Wait for interrupt mode

When an internal or external interrupt request occurs, the CPU wakes up from Wait mode,

serves the interrupt routine and resumes processing.

The following list gives examples of peripherals or features with interrupts having exit-from-

wait capability:

●

ProxSense

●

I2C

●

USART

●

SPI

●

AWU

●

External interrupt

●

Timers

Refer to the STM8TL5xxx reference manual (RM0312) for more details.

4.6.3

Exiting Wait for event mode

When an internal or external event request occurs, the CPU wakes up from Wait mode and

resumes processing.

The following list gives examples of peripherals or features with events having exit-from-wait

capability:

●

ProxSense

●

I2C

●

USART

●

SPI

●

External interrupt

●

Timers

If an interrupt occurs during Wait for event mode, the related interrupt service routine is

executed. After this routine, the MCU goes back to Wait for event mode.

Refer to the STM8TL5xxx reference manual (RM0312) for more details.

4.7

Halt mode

In this mode the system clock is stopped. This means that the CPU and all the peripherals

requiring clocks are disabled, except for the following cases:

●

The HSI clock is not stopped if used by the SWIM

●

The system clock source is not stopped if a Flash/Data EEPROM write operation is in

progress.

●

The LSI clock is not stopped if used by the SWIM, by the IWDG or if the “IWDG_HALT”

option bit is disabled.

In Halt mode, none of the peripherals is clocked and the digital part of the MCU consumes

almost no power.