/**
@page TIM_PWMOutput_Init TIM example
@verbatim
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
* @file Examples_LL/TIM/TIM_PWMOutput_Init/readme.txt
* @author MCD Application Team
* @brief Description of the TIM_PWMOutput_Init example.
******************************************************************************
* @attention
*
* Copyright (c) 2016 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Example Description
Use of a timer peripheral to generate a
PWM output signal and update the PWM duty cycle. This example is based on the
STM32F3xx TIM LL API. The peripheral initialization uses
LL initialization function to demonstrate LL init.
In this example TIM2 input clock TIM2CLK is set to APB1 clock (PCLK1),
since APB1 pre-scaler is equal to 1.
TIM2CLK = PCLK1
PCLK1 = HCLK
=> TIM2CLK = HCLK = SystemCoreClock (64 MHz)
To set the TIM2 counter clock frequency to 10 KHz, the pre-scaler (PSC) is
calculated as follows:
PSC = (TIM2CLK / TIM2 counter clock) - 1
PSC = (SystemCoreClock /10 KHz) - 1
SystemCoreClock is set to 64 MHz for STM32F3xx Devices.
Auto-reload (ARR) is calculated to get a time base period of 10 ms,
meaning a time base frequency of 100 Hz.
ARR = (TIM2 counter clock / time base frequency) - 1
ARR = (TIM2 counter clock / 100) - 1
Initially, the capture/compare register (CCR1) of the output channel is set to
half the auto-reload value meaning a initial duty cycle of 50%.
Generally speaking this duty cycle is calculated as follows:
Duty cycle = (CCR1 / ARR) * 100
The timer output channel is mapped on the pin PA.05 (connected to LED2 on board
STM32F334R8-Nucleo Rev C). Thus LED2 status (on/off) mirrors the timer output
level (active v.s. inactive).
User push-button can be used to change the duty cycle from 0% up to 100% by
steps of 10%. Duty cycle is periodically measured. It can be observed through
the debugger by watching the variable uwMeasuredDutyCycle.
Initially the output channel is configured in output compare toggle mode.
@note The LED2 is not toggling. In fact, if the dutycycle is 0% so the LED2 is OFF. When pushing
successively the user button, the LED2 is ON and its luminosity rises as the dutycycle value keep
increasing.
@par Directory contents
- TIM/TIM_PWMOutput_Init/Inc/stm32f3xx_it.h Interrupt handlers header file
- TIM/TIM_PWMOutput_Init/Inc/main.h Header for main.c module
- TIM/TIM_PWMOutput_Init/Inc/stm32_assert.h Template file to include assert_failed function
- TIM/TIM_PWMOutput_Init/Src/stm32f3xx_it.c Interrupt handlers
- TIM/TIM_PWMOutput_Init/Src/main.c Main program
- TIM/TIM_PWMOutput_Init/Src/system_stm32f3xx.c STM32F3xx system source file
@par Hardware and Software environment
- This example runs on STM32F334x8 devices.
- This example has been tested with STM32F334R8-Nucleo Rev C 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
*/
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