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111 lines
5.0 KiB
Plaintext
111 lines
5.0 KiB
Plaintext
/**
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@page TIM_PWMOutput TIM PWM Output example
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@verbatim
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******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
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* @file TIM/TIM_PWMOutput/readme.txt
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* @author MCD Application Team
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* @brief Description of the PWM signals generation using TIM3
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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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This example shows how to configure the TIM peripheral in PWM (Pulse Width Modulation)
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mode.
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SystemCoreClock is set to 72 MHz for STM32F3xx Devices.
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In this example TIM3 input clock (TIM3CLK) is set to 2 * APB1 clock (PCLK1),
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since APB1 prescaler is different from 1.
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TIM3CLK = 2 * PCLK1
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PCLK1 = HCLK / 2
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=> TIM3CLK = HCLK = SystemCoreClock
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To get TIM3 counter clock at 24 MHz, the prescaler is computed as follows:
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Prescaler = (TIM3CLK / TIM3 counter clock) - 1
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Prescaler = (SystemCoreClock /24 MHz) - 1
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To get TIM3 output clock at 36 KHz, the period (ARR)) is computed as follows:
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ARR = (TIM3 counter clock / TIM3 output clock) - 1
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= 665
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TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%
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TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%
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TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%
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TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%
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The PWM waveforms can be displayed using an oscilloscope.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application need to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Directory contents
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- TIM/TIM_PWMOutput/Inc/stm32f3xx_hal_conf.h HAL configuration file
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- TIM/TIM_PWMOutput/Inc/stm32f3xx_it.h Interrupt handlers header file
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- TIM/TIM_PWMOutput/Inc/main.h Header for main.c module
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- TIM/TIM_PWMOutput/Src/stm32f3xx_it.c Interrupt handlers
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- TIM/TIM_PWMOutput/Src/main.c Main program
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- TIM/TIM_PWMOutput/Src/stm32f3xx_hal_msp.c HAL MSP file
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- TIM/TIM_PWMOutput/Src/system_stm32f3xx.c STM32F3xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F373xC devices.
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- In this example, the clock is set to 72 MHz.
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- This example has been tested with STMicroelectronics STM32373C-EVAL RevB
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board and can be easily tailored to any other supported device
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and development board.
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- STM32373C-EVAL RevB Set-up
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Connect the following pins to an oscilloscope to monitor the different waveforms:
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- TIM3_CH1 : PC.06
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- TIM3_CH2 : PC.07
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- TIM3_CH3 : PC.08
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- TIM3_CH4 : PC.09
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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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