/**
@page TIM_PWMOutput TIM PWM Output example
@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file TIM/TIM_PWMOutput/readme.txt
* @author MCD Application Team
* @brief Description of the PWM signals generation using TIM8
******************************************************************************
* @attention
*
* Copyright (c) 2017 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
This example shows how to configure the TIM peripheral in PWM (Pulse Width Modulation)
mode.
SystemCoreClock is set to 180 MHz for STM32F4xx Devices.
In this example TIM8 input clock (TIM8CLK) is set to APB2 clock x 2,
since APB2 prescaler is equal to 2.
TIM8CLK = APB2CLK*2
APB2CLK = HCLK/2
=> TIM8CLK = HCLK = SystemCoreClock
To get TIM8 counter clock at 16 MHz, the prescaler is computed as follows:
Prescaler = (TIM8CLK / TIM8 counter clock) - 1
Prescaler = ((SystemCoreClock) /16 MHz) - 1
To get TIM8 output clock at 24 KHz, the period (ARR)) is computed as follows:
ARR = (TIM8 counter clock / TIM8 output clock) - 1
= 665
TIM8 Channel1 duty cycle = (TIM8_CCR1/ TIM8_ARR + 1)* 100 = 50%
TIM8 Channel2 duty cycle = (TIM8_CCR2/ TIM8_ARR + 1)* 100 = 37.5%
TIM8 Channel3 duty cycle = (TIM8_CCR3/ TIM8_ARR + 1)* 100 = 25%
TIM8 Channel4 duty cycle = (TIM8_CCR4/ TIM8_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.
@note The connection of the LCD reset pin to a dedicated GPIO PK7 instead of the STM32F469 NRST pin may cause residual display on LCD with applications/examples that do not require display.
The LCD clear can be ensured by hardware through the boards power off/power on or by software calling the BSP_LCD_Reset() function.
@par Keywords
Timers, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
@par Directory contents
- TIM/TIM_PWMOutput/Inc/stm32f4xx_hal_conf.h HAL configuration file
- TIM/TIM_PWMOutput/Inc/stm32f4xx_it.h Interrupt handlers header file
- TIM/TIM_PWMOutput/Inc/main.h Header for main.c module
- TIM/TIM_PWMOutput/Src/stm32f4xx_it.c Interrupt handlers
- TIM/TIM_PWMOutput/Src/main.c Main program
- TIM/TIM_PWMOutput/Src/stm32f4xx_hal_msp.c HAL MSP file
- TIM/TIM_PWMOutput/Src/system_stm32f4xx.c STM32F4xx system source file
@par Hardware and Software environment
- This example runs on STM32F469xx/STM32F479xx devices.
- In this example, the clock is set to 180 MHz.
- This example has been tested and validated with STMicroelectronics STM32469I-EVAL RevC
board and can be easily tailored to any other supported device
and development board.
- STM32469I-EVAL Set-up
Connect the following pins to an oscilloscope to monitor the different waveforms:
- TIM8_CH1 : PC.06 (pin 58 in CN6 connector)
- TIM8_CH2 : PC.07 (pin 56 in CN6 connector)
- TIM8_CH3 : PC.08 (pin 51 in CN6 connector)
- TIM8_CH4 : PC.09 (pin 46 in CN6 connector)
@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
*/
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