AN3133 datasheet(32/43 Pages) STMICROELECTRONICS

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Application examples

AN3133

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Doc ID 16956 Rev 5

Figure 17.

Wakeup from low power mode example: RTC ISR flowchart

6.3

Example 3: Periodic event generation using the wakeup unit

This example explains how to configure the RTC periodic wakeup unit event to toggle LEDs

every 500 ms.

The LSE clock is the RTCCLK source (default RTC clock) and the wakeup timer clock

selection is configured to RTCCLK/16 (WUCKSEL[2:0]= 000b) to obtains a wakeup period

resolution of 488.28125 µs. The wakeup unit 16-bit timer downcounter is loaded with 1023

to generate a periodic event every 500 ms (see equation below).

Periodic event = (Timer_DownCounter +1) x Timer_resolution = 1024 step = 500 ms

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

STM8AL3Lx standard peripheral library available from

STM8l15x_StdPeriph_Lib.zip\Project\STM8L15x_StdPeriph_Examples\RTC\RTC_Periodic

Wakeup500ms\

6.4

Example 4: Tamper detection

This example provides a short description of how to use the RTC peripheral's tamper

detection features: sample duration, filter, and number of samples to wait for before the

Tamper event.

The user can manipulate the application using the Tamper, Key and Joystick navigation

buttons.

After startup, 2 counters (00:000 00:000) are displayed on the LCD. Both of them consist of

2 fields [seconds on 2 digits]:[milliseconds on 3 digits].

The first counter is used to store the time when the key button is pressed.

The second counter is used to display the current time.

Clear wakeup

interrupt pending bit

Return to the Main program

RTC Interrupt Routine

ai17273

AN3133 Datasheet(PDF) 32 Page - STMicroelectronics