83 lines
3.1 KiB
Plaintext
83 lines
3.1 KiB
Plaintext
/**
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@page TIM_DMA TIM example
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@verbatim
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******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
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* @file Examples_LL/TIM/TIM_DMA/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM_DMA example.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2016 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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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 STM32F1xx 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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- TIM3CLK = SystemClock
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- Counter repetition = 3
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- Prescaler = 0
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- TIM3 counter clock = SystemClock
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- SystemCoreClock is set to 72 MHz for STM32F1xx Devices.
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The objective is to configure TIM3 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 TIM3 Repetition counter,
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each 4 Update Requests, the TIM3 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 80 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 Directory contents
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- TIM/TIM_DMA/Inc/stm32f1xx_it.h Interrupt handlers header file
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- TIM/TIM_DMA/Inc/main.h Header for main.c module
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- TIM/TIM_DMA/Inc/stm32_assert.h Template file to include assert_failed function
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- TIM/TIM_DMA/Src/stm32f1xx_it.c Interrupt handlers
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- TIM/TIM_DMA/Src/main.c Main program
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- TIM/TIM_DMA/Src/system_stm32f1xx.c STM32F1xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F103xB devices.
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- This example has been tested with STM32F103RB-Nucleo board and can be
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easily tailored to any other supported device and development board.
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- STM32F103RB-Nucleo Set-up
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- Connect TIM3 pin to the oscilloscope to monitor the generated waveform:
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- TIM3_CH3 PB.00: connected to pin 4 of CN8 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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