111 lines
4.5 KiB
Plaintext
111 lines
4.5 KiB
Plaintext
/**
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@page TIM_PWMOutput TIM PWM Output example
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@verbatim
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******************************************************************************
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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 TIM1
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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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This example shows how to configure the TIM peripheral in PWM (Pulse Width Modulation)
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mode.
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At the beginning of the main program the HAL_Init() function is called to reset
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all the peripherals, initialize the Flash interface and the systick.
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The SystemClock_Config() function is used to configure the system clock for STM32WL55JCIx Devices :
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The CPU at 48 MHz
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SystemCoreClock is set to 48 MHz for STM32WLxx Devices.
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In this example TIM1 input clock (TIM1CLK) is set to APB1 clock (PCLK1),
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since APB1 prescaler is equal to 1.
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TIM1CLK = PCLK1
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PCLK1 = HCLK
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=> TIM1CLK = HCLK = SystemCoreClock
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To get TIM1 counter clock at 1 MHz, the prescaler is computed as follows:
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Prescaler = (TIM1CLK / TIM1 counter clock) - 1
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Prescaler = ((SystemCoreClock) /1 MHz) - 1
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To get TIM1 output clock at 25 KHz, the period (ARR)) is computed as follows:
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ARR = (TIM1 counter clock / TIM1 output clock) - 1
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= 39
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TIM1 Channel1 duty cycle = (TIM1_CCR1/ TIM1_ARR + 1)* 100 = 50%
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TIM1 Channel2 duty cycle = (TIM1_CCR2/ TIM1_ARR + 1)* 100 = 37.5%
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TIM1 Channel3 duty cycle = (TIM1_CCR3/ TIM1_ARR + 1)* 100 = 25%
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TIM1 Channel4 duty cycle = (TIM1_CCR4/ TIM1_ARR + 1)* 100 = 12.5%
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LED3 is ON when there are an error.
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The PWM waveforms can be displayed using an oscilloscope.
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@note The duty cycles values mentioned above are theoretical (obtained when the system clock frequency is exactly 48 MHz).
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They might be slightly different depending on system clock frequency precision.
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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 This example needs 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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Timer, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
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@par Directory contents
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- TIM/TIM_PWMOutput/Inc/stm32wlxx_nucleo_conf.h BSP configuration file
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- TIM/TIM_PWMOutput/Inc/stm32wlxx_hal_conf.h HAL configuration file
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- TIM/TIM_PWMOutput/Inc/stm32wlxx_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/stm32wlxx_it.c Interrupt handlers
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- TIM/TIM_PWMOutput/Src/main.c Main program
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- TIM/TIM_PWMOutput/Src/stm32wlxx_hal_msp.c HAL MSP file
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- TIM/TIM_PWMOutput/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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- In this example, the clock is set to 48 MHz.
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- This example has been tested with STMicroelectronics NUCLEO-WL55JC RevC
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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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- NUCLEO-WL55JC RevC Set-up
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Connect the following pins to an oscilloscope to monitor the different waveforms:
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- TIM1_CH1 : PA.08 (pin 16 in CN10 connector)
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- TIM1_CH2 : PA.09 (pin 19 in CN10 connector)
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- TIM1_CH3 : PA.10 (pin 32 in CN7 connector)
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- TIM1_CH4 : PA.11 (pin 5 in CN10 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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