ST STM8L1528-EVAL, User Manual, Page: 15 / 23

UM1000 Demonstration applications
Doc ID 17964 Rev 1 15/23
Figure 28. Active Halt wait for EXTI message
The MCU remains in Active-halt mode unless the SEL button is pressed. When SEL is
pressed, the MCU exits from Active-halt mode, the system clock frequency is set to
16 MHz, and the application execution resumes.
The following message is displayed on the LCD screen:
Figure 29. Exit from Active-halt with EXTI message
Note: If an alarm occurs when the system is in Active-halt mode, it is delayed until the EXTI
interrupt wakes up the device; then all LEDs are ON and a sound is played for ~10s.
●
The RTC alarm wakes up the MCU from Active-halt mode.
The LEDs blink until SEL is pressed from the Active-halt menu (see Figure 30 ). The
system then enters Active-halt mode and the following message is displayed on the
LCD.
Figure 30. Active Halt wait for alarm message
When the alarm time is reached, the system exits from Active-halt mode, the system
clock frequency is set to 16 MHz, and the application execution resumes. The message
shown in
Figure 31 is displayed:
Figure 31. Exit from Active-halt with alarm message
Exit: EXTI
Press SEL
ActiveHalt Mode
Exit: EXTI
ActiveHalt mode
Wait for ALARM
ActiveHalt mode
Exit: RTC Alarm
www.BDTIC.com/ST