86 lines
3.4 KiB
Plaintext
86 lines
3.4 KiB
Plaintext
/**
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@page TIM_DMA_Init TIM example
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@verbatim
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******************************************************************************
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* @file Examples_LL/TIM/TIM_DMA_Init/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM_DMA_Init example.
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******************************************************************************
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*
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* Copyright (c) 2020 STMicroelectronics. All rights reserved.
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*
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* This software component is licensed by ST under BSD 3-Clause license,
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* the "License"; You may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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* opensource.org/licenses/BSD-3-Clause
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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 the DMA with a timer update request
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to transfer data from memory to Timer Capture Compare Register 3 (TIMx_CCR3). This
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example is based on the STM32WLxx TIM LL API. The peripheral initialization
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uses LL unitary service functions for optimization purposes (performance and size).
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The following configuration values are used in this example:
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- TIM1CLK = SystemClock
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- Counter repetition = 3
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- Prescaler = 0
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- TIM1 counter clock = SystemClock
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- SystemCoreClock is set to 48 MHz for STM32WLxx Devices.
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The objective is to configure TIM1 channel 3 to generate PWM edge aligned
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signal with a frequency equal to 17.57 KHz, and a variable duty cycle that
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is changed by the DMA after a specific number of Update DMA request.
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The number of this repetitive requests is defined by the TIM1 Repetition counter,
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each 4 Update Requests, the TIM1 Channel 3 Duty Cycle changes to the next new
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value defined by the aCCValue buffer.
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The PWM waveform can be displayed using an oscilloscope.
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Whenever a DMA transfer fails LED2 flashes with a frequency of 1 Hz.
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@note PWM signal frequency value mentioned above is theoretical (obtained when
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the system clock frequency is exactly 48 MHz). Since the generated system
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clock frequency may vary from one board to another observed PWM signal
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frequency might be slightly different.
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@par Keywords
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Timers, DMA, PWM, Frequency, Duty Cycle, Waveform, Oscilloscope, Output, Signal
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@par Directory contents
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- TIM/TIM_DMA_Init/Inc/stm32wlxx_it.h Interrupt handlers header file
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- TIM/TIM_DMA_Init/Inc/main.h Header for main.c module
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- TIM/TIM_DMA_Init/Inc/stm32_assert.h Template file to include assert_failed function
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- TIM/TIM_DMA_Init/Src/stm32wlxx_it.c Interrupt handlers
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- TIM/TIM_DMA_Init/Src/main.c Main program
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- TIM/TIM_DMA_Init/Src/system_stm32wlxx.c STM32WLxx system source file
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@par Hardware and Software environment
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- This example runs on STM32WL55JCIx devices.
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- This example has been tested with NUCLEO-WL55JC RevC board and can be
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easily tailored to any other supported device and development board.
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- NUCLEO-WL55JC RevC Set-up
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- Connect the TIM1 pins to an oscilloscope to monitor the different waveforms:
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- TIM1_CH3 PA.10: connected to pin 32 of CN7 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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* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
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*/
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