/**
@page TIM_PWMOutput TIM PWM Output example
@verbatim
******************************************************************************
* @file TIM/TIM_PWMOutput/readme.txt
* @author MCD Application Team
* @brief Description of the PWM signals generation using TIM4
******************************************************************************
* @attention
*
* Copyright (c) 2016 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim
@par Example Description
Configuration of the TIM peripheral in PWM (pulse width modulation) mode.
SystemCoreClock is set to 216 MHz for STM32F7xx Devices.
In this example TIM4 input clock (TIM4CLK) is set to APB1 clock x 2,
since APB1 prescaler is equal to 4.
TIM4CLK = APB1CLK*2
APB1CLK = HCLK/4
=> TIM4CLK = HCLK/2 = SystemCoreClock/2
To get TIM4 counter clock at 21.6 MHz, the prescaler is computed as follows:
Prescaler = (TIM4CLK / TIM4 counter clock) - 1
Prescaler = ((SystemCoreClock/2) /21.6 MHz) - 1
To get TIM4 output clock at 24 KHz, the period (ARR)) is computed as follows:
ARR = (TIM4 counter clock / TIM4 output clock) - 1
= 899
TIM4 Channel1 duty cycle = (TIM4_CCR1/ TIM4_ARR + 1)* 100 = 50%
TIM4 Channel2 duty cycle = (TIM4_CCR2/ TIM4_ARR + 1)* 100 = 37.5%
TIM4 Channel3 duty cycle = (TIM4_CCR3/ TIM4_ARR + 1)* 100 = 25%
TIM4 Channel4 duty cycle = (TIM4_CCR4/ TIM4_ARR + 1)* 100 = 12.5%
The PWM waveforms can be displayed using an oscilloscope.
@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Timers, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
<20><><A0><A0><A0>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<0A><><A0><A0><A0><A0>The address and the size of cacheable buffers (shared between CPU and other masters) must be properly updated to be aligned to cache line size (32 bytes).
@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
<0A><><A0><A0><A0> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
<0A><><A0><A0><A0><A0>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
<0A><><A0><A0><A0><A0>Even though the user must manage the cache coherence for read accesses.
<0A><><A0><A0><A0><A0>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
<0A><><A0><A0><A0><A0>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
@par Directory contents
- TIM/TIM_PWMOutput/Inc/stm32f7xx_hal_conf.h HAL configuration file
- TIM/TIM_PWMOutput/Inc/stm32f7xx_it.h Interrupt handlers header file
- TIM/TIM_PWMOutput/Inc/main.h Header for main.c module
- TIM/TIM_PWMOutput/Src/stm32f7xx_it.c Interrupt handlers
- TIM/TIM_PWMOutput/Src/main.c Main program
- TIM/TIM_PWMOutput/Src/stm32f7xx_hal_msp.c HAL MSP file
- TIM/TIM_PWMOutput/Src/system_stm32f7xx.c STM32F7xx system source file
@par Hardware and Software environment
- This example runs on STM32F769xx/STM32F779xx/STM32F777xx/STM32F767xx devices.
- In this example, the clock is set to 216 MHz.
- This example has been tested with STMicroelectronics STM327F69I-EVAL
board and can be easily tailored to any other supported device
and development board.
- STM32F769I-EVAL Set-up
Connect the following pins to an oscilloscope to monitor the different waveforms:
- TIM4_CH1 : PB.06
- TIM4_CH2 : PB.07
- TIM4_CH3 : PB.08
- TIM4_CH4 : PB.09
@par How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the example
*/
767d083e20