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106 lines
4.7 KiB
Plaintext
106 lines
4.7 KiB
Plaintext
/**
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@page TIM_PWMOutput_Init TIM example
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@verbatim
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******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
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* @file Examples_LL/TIM/TIM_PWMOutput_Init/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM_PWMOutput_Init example.
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******************************************************************************
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. Neither the name of STMicroelectronics nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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Use of a timer peripheral to generate a
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PWM output signal and update the PWM duty cycle. This example is based on the
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STM32F0xx TIM LL API. The peripheral initialization uses
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LL initialization function to demonstrate LL init.
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In this example TIM2 input clock TIM2CLK is set to APB1 clock (PCLK1),
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since APB1 pre-scaler is equal to 1.
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TIM2CLK = PCLK1
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PCLK1 = HCLK
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=> TIM2CLK = HCLK = SystemCoreClock (48 MHz)
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To set the TIM2 counter clock frequency to 10 KHz, the pre-scaler (PSC) is
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calculated as follows:
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PSC = (TIM2CLK / TIM2 counter clock) - 1
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PSC = (SystemCoreClock /10 KHz) - 1
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SystemCoreClock is set to 48 MHz for STM32F0xx Devices.
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Auto-reload (ARR) is calculated to get a time base period of 10 ms,
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meaning a time base frequency of 100 Hz.
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ARR = (TIM2 counter clock / time base frequency) - 1
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ARR = (TIM2 counter clock / 100) - 1
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Initially, the capture/compare register (CCR1) of the output channel is set to
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half the auto-reload value meaning a initial duty cycle of 50%.
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Generally speaking this duty cycle is calculated as follows:
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Duty cycle = (CCR1 / ARR) * 100
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The timer output channel is mapped on the pin PA.05 (connected to LED2 on board
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STM32F072RB-Nucleo RevC). Thus LED2 status (on/off) mirrors the timer output
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level (active v.s. inactive).
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User push-button can be used to change the duty cycle from 0% up to 100% by
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steps of 10%. Duty cycle is periodically measured. It can be observed through
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the debugger by watching the variable uwMeasuredDutyCycle.
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Initially the output channel is configured in output compare toggle mode.
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@note The LED2 is not toggling. In fact, if the dutycycle is 0% so the LED2 is OFF. When pushing
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successively the user button, the LED2 is ON and its luminosity rises as the dutycycle value keep
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increasing.
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@par Directory contents
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- TIM/TIM_PWMOutput_Init/Inc/stm32f0xx_it.h Interrupt handlers header file
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- TIM/TIM_PWMOutput_Init/Inc/main.h Header for main.c module
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- TIM/TIM_PWMOutput_Init/Inc/stm32_assert.h Template file to include assert_failed function
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- TIM/TIM_PWMOutput_Init/Src/stm32f0xx_it.c Interrupt handlers
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- TIM/TIM_PWMOutput_Init/Src/main.c Main program
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- TIM/TIM_PWMOutput_Init/Src/system_stm32f0xx.c STM32F0xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F072xB devices.
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- This example has been tested with STM32F072RB-Nucleo RevC board and can be
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easily tailored to any other supported device and development board.
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
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*/
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