101 lines
3.8 KiB
Plaintext
101 lines
3.8 KiB
Plaintext
/**
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@page TIM_PWMOutput TIM PWM Output example
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@verbatim
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******************** (C) COPYRIGHT 2017 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 TIM4
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2017 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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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 100 MHz for STM32F4xx Devices.
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In this example TIM4 input clock (TIM4CLK) is set to APB1 clock x 2,
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since APB1 prescaler is equal to 2.
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TIM4CLK = APB1CLK*2
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APB1CLK = HCLK/2
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=> TIM4CLK = HCLK = SystemCoreClock
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To get TIM4 counter clock at 16 MHz, the prescaler is computed as follows:
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Prescaler = (TIM4CLK / TIM4 counter clock) - 1
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Prescaler = ((SystemCoreClock) /16 MHz) - 1
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To get TIM4 output clock at 24 KHz, the period (ARR)) is computed as follows:
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ARR = (TIM4 counter clock / TIM4 output clock) - 1
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= 665
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TIM4 Channel1 duty cycle = (TIM4_CCR1/ TIM4_ARR + 1)* 100 = 50%
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TIM4 Channel2 duty cycle = (TIM4_CCR2/ TIM4_ARR + 1)* 100 = 37.5%
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TIM4 Channel3 duty cycle = (TIM4_CCR3/ TIM4_ARR + 1)* 100 = 25%
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TIM4 Channel4 duty cycle = (TIM4_CCR4/ TIM4_ARR + 1)* 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 Keywords
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Timers, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
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@par Directory contents
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- TIM/TIM_PWMOutput/Inc/stm32f4xx_hal_conf.h HAL configuration file
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- TIM/TIM_PWMOutput/Inc/stm32f4xx_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/stm32f4xx_it.c Interrupt handlers
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- TIM/TIM_PWMOutput/Src/main.c Main program
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- TIM/TIM_PWMOutput/Src/stm32f4xx_hal_msp.c HAL MSP file
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- TIM/TIM_PWMOutput/Src/system_stm32f4xx.c STM32F4xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F412xG devices.
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- In this example, the clock is set to 100 MHz.
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- This example has been tested with STMicroelectronics STM32412G-DISCOVERY
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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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- STM32412G-DISCOVERY Set-up
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Connect the following pins to an oscilloscope to monitor the different waveforms:
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- TIM4_CH1 : PB.06 (pin 23 in P2 connector)
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- TIM4_CH2 : PB.07 (pin 24 in P2 connector)
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- TIM4_CH3 : PB.08 (pin 19 in P2 connector)
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- TIM4_CH4 : PB.09 (pin 20 in P2 connector)
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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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*/
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