92 lines
3.9 KiB
Plaintext
92 lines
3.9 KiB
Plaintext
/**
|
|
@page LPTIM_Timeout LPTIM Timeout example with LSE clock source
|
|
|
|
@verbatim
|
|
******************************************************************************
|
|
* @file LPTIM/LPTIM_Timeout/readme.txt
|
|
* @author MCD Application Team
|
|
* @brief Description of the LPTIM Timeout example.
|
|
******************************************************************************
|
|
*
|
|
* Copyright (c) 2020 STMicroelectronics. All rights reserved.
|
|
*
|
|
* This software component is licensed by ST under BSD 3-Clause license,
|
|
* the "License"; You may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at:
|
|
* opensource.org/licenses/BSD-3-Clause
|
|
*
|
|
******************************************************************************
|
|
@endverbatim
|
|
|
|
@par Example Description
|
|
|
|
How to implement, through the HAL LPTIM API, a timeout with the LPTIMER peripheral, to wake up
|
|
the system from a low-power mode.
|
|
|
|
|
|
The main() function configures the LPTIMER and goes in STOP mode.
|
|
In order to start the timer a first trigger is needed on (PC3)(LPTIM_ETR).
|
|
Any successive trigger event on (PC3) will reset the counter and the timer
|
|
will restart. The timeout value corresponds to the compare value (32768).
|
|
If after the first trigger no other trigger occurs within the expected time frame,
|
|
the MCU is woken-up by the compare match event and LED2 toggles.
|
|
|
|
In this example the LPTIM is clocked by the LSE
|
|
|
|
Timeout = (Compare + 1) / LPTIM_Clock
|
|
= (32767 + 1) / LSE_Clock_Frequency
|
|
|
|
Once the system is woken up it remains in run mode. The led keeps toggling each time the timer expires.
|
|
|
|
@note This example can not be used in DEBUG mode, this is due to the fact
|
|
that the Cortex-M4 core is no longer clocked during low power mode
|
|
so debugging features are disabled.
|
|
|
|
@note Care must be taken when using HAL_Delay(), this function provides accurate
|
|
delay (in milliseconds) based on variable incremented in SysTick ISR. This
|
|
implies that if HAL_Delay() is called from a peripheral ISR process, then
|
|
the SysTick interrupt must have higher priority (numerically lower)
|
|
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
|
|
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
|
|
|
|
@note This example needs to ensure that the SysTick time base is always set to 1 millisecond
|
|
to have correct HAL operation.
|
|
|
|
@par Keywords
|
|
|
|
Timer, Low Power Timer, Wake up, Stop mode, LSI, Run mode
|
|
|
|
@par Directory contents
|
|
|
|
- LPTIM/LPTIM_Timeout/Inc/stm32wlxx_nucleo_conf.h BSP configuration file
|
|
- LPTIM/LPTIM_Timeout/Inc/stm32wlxx_hal_conf.h HAL configuration file
|
|
- LPTIM/LPTIM_Timeout/Inc/stm32wlxx_it.h Interrupt handlers header file
|
|
- LPTIM/LPTIM_Timeout/Inc/main.h Header for main.c module
|
|
- LPTIM/LPTIM_Timeout/Src/stm32wlxx_it.c Interrupt handlers
|
|
- LPTIM/LPTIM_Timeout/Src/main.c Main program
|
|
- LPTIM/LPTIM_Timeout/Src/stm32wlxx_hal_msp.c HAL MSP module
|
|
- LPTIM/LPTIM_Timeout/Src/system_stm32wlxx.c STM32WLxx system source file
|
|
|
|
|
|
@par Hardware and Software environment
|
|
|
|
- This example runs on STM32WL55JCIx devices.
|
|
|
|
- This example has been tested with STMicroelectronics NUCLEO-WL55JC RevC
|
|
board and can be easily tailored to any other supported device
|
|
and development board.
|
|
|
|
- Connect an external trigger (ETR) to PC3(pin 38 in CN10 connector).
|
|
If the trigger is higher than 1Hz, the counter is regularly reset, the system stays in STOP mode.
|
|
If the trigger is lower than 1Hz, the counter expires and the system is woken up.
|
|
|
|
@par How to use it ?
|
|
|
|
In order to make the program work, you must do the following :
|
|
- Open your preferred tool chain
|
|
- Rebuild all files and load your image into target memory
|
|
- Run the example
|
|
|
|
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
|
|
*/
|