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AN3133

Application examples

Doc ID 16956 Rev 5

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6.2

Example 2: Wakeup from low power mode

This example explains how to use the STM8L15xx LCD embedded controller to drive the

LCD glass mounted on STM8L1526-EVAL and STM8L1528-EVAL boards and how to exit

the MCU from Active-halt mode using the wakeup unit.

This example is delivered within the STM8L05x/STM8L15x/STM8L16x/STM8AL31x/

STM8AL3Lx standard peripheral library available from http://wwwst.com/stm8l (documents

and files for the STM8L family). It is located at

STM8l15x_StdPeriph_Lib.zip\Project\STM8L15x_StdPeriph_Examples\LCD\

LCD_SegmentsDrive\.

This example performs the following actions:

The first step consists in displaying an ‘STM8L’ string on the LCD display in scrolling

mode.

The ‘LP MODE’ string is then displayed, and the MCU enters Active-halt mode.

After 20 seconds the MCU is woken up from Active-halt mode by the RTC wakeup

event and continues processing.

These steps are executed in an infinite loop.

The flowcharts of this example are presented in Figure 16 and Figure 17.

Figure 16.

Wakeup from low power mode example: main program flowchart

Init LCD Glass

Display the ‘STM8L’ string on

LCD glass in scrolling mode

Display ‘LP MODE’ string on LCD

glass and Enter Active-halt mode

Set RTC wake up counter to

20 ticks (20 s)

Enab le RTC clock

Init RTC wake up unit clock

(1 counter tick = 1 second)

Enable Wakeup unit interrupt

Enable the Wakeup unit

START Main Program

ai17272

Disable the Wakeup unit

AN3133 데이터시트(PDF) 31 Page - STMicroelectronics