/**
@page TIM_TimeBase_Init TIM example
@verbatim
******************************************************************************
* @file Examples_LL/TIM/TIM_TimeBase_Init/readme.txt
* @author MCD Application Team
* @brief Description of the TIM_TimeBase_Init 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
Configuration of the TIM peripheral to generate a timebase. This
example is based on the STM32WLxx TIM LL API. The peripheral initialization
uses LL unitary service functions for optimization purposes (performance and size).
In this example TIM1 input clock TIM1CLK is set to APB2 clock (PCLK2),
since APB2 pre-scaler is equal to 1.
TIM1CLK = PCLK2
PCLK2 = HCLK
=> TIM1CLK = SystemCoreClock (48 MHz)
To set the TIM1 counter clock frequency to 10 KHz, the pre-scaler (PSC) is calculated as follows:
PSC = (TIM1CLK / TIM1 counter clock) - 1
PSC = (SystemCoreClock /10 KHz) - 1
SystemCoreClock is set to 48 MHz for STM32WLxx Devices.
The auto-reload (ARR) is calculated to get a timebase period of 100ms,
meaning that initial timebase frequency is 10 Hz.
ARR = (TIM1 counter clock / timebase frequency) - 1
ARR = (TIM1 counter clock / 10) - 1
Update interrupts are enabled. Within the update interrupt service routine, pin PB9
(connected to LED2 on board NUCLEO-WL55JC RevC) is toggled. So the period of
blinking of LED2 = 2 * timebase period.
User push-button (B1) can be used to modify the timebase period from 100 ms
to 1 s in 100 ms steps. To do so, every time User push-button (B1) is pressed, the
autoreload register (ARR) is updated. In up-counting update event is generated
at each counter overflow (when the counter reaches the auto-reload value).
Finally the timebase frequency is calculated as follows:
timebase frequency = TIM1 counter clock /((PSC + 1)*(ARR + 1)*(RCR + 1))
@par Keywords
Timer, TIM, timebase, Interrupt, Clock source
@par Directory contents
- TIM/TIM_TimeBase_Init/Inc/stm32wlxx_it.h Interrupt handlers header file
- TIM/TIM_TimeBase_Init/Inc/main.h Header for main.c module
- TIM/TIM_TimeBase_Init/Inc/stm32_assert.h Template file to include assert_failed function
- TIM/TIM_TimeBase_Init/Src/stm32wlxx_it.c Interrupt handlers
- TIM/TIM_TimeBase_Init/Src/main.c Main program
- TIM/TIM_TimeBase_Init/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 NUCLEO-WL55JC RevC board and can be
easily tailored to any other supported device and development board.
@par How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the example
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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