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/**
@page TIM_PWMOutput TIM example
@verbatim
******************************************************************************
* @file Examples_LL/TIM/TIM_PWMOutput/readme.txt
* @author MCD Application Team
* @brief Description of the TIM_PWMOutput example.
******************************************************************************
*
* Copyright (c) 2019 STMicroelectronics. All rights reserved.
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
@endverbatim
@par Example Description
Use of a timer peripheral to generate a
PWM output signal and update the PWM duty cycle. This example is based on the
STM32WBxx TIM LL API. The peripheral initialization uses
LL unitary service functions for optimization purposes (performance and size).
In this example TIM2 input clock TIM2CLK is set to APB1 clock (PCLK1),
since APB1 pre-scaler is equal to 1.
TIM2CLK = PCLK1
PCLK1 = HCLK
=> TIM2CLK = HCLK = SystemCoreClock (64 MHz)
To set the TIM2 counter clock frequency to 10 KHz, the pre-scaler (PSC) is
calculated as follows:
PSC = (TIM2CLK / TIM2 counter clock) - 1
PSC = (SystemCoreClock /10 KHz) - 1
SystemCoreClock is set to 64 MHz for STM32WBxx Devices.
Auto-reload (ARR) is calculated to get a time base period of 10 ms,
meaning a time base frequency of 100 Hz.
ARR = (TIM2 counter clock / time base frequency) - 1
ARR = (TIM2 counter clock / 100) - 1
Initially, the capture/compare register (CCR1) of the output channel is set to
half the auto-reload value meaning a initial duty cycle of 50%.
Generally speaking this duty cycle is calculated as follows:
Duty cycle = (CCR1 / ARR) * 100
The timer output channel must be connected to LED2 on board P-NUCLEO-WB55.
Thus LED2 status (on/off) mirrors the timer output level (active v.s. inactive).
User push-button (SW1) can be used to change the duty cycle from 0% up to 100% by
steps of 10%. Duty cycle is periodically measured. It can be observed through
the debugger by watching the variable uwMeasuredDutyCycle.
@note The LED2 is not toggling. In fact, if the dutycycle is 0% so the LED2 is OFF. When pushing
successively the user button, the LED2 is ON and its luminosity rises as the dutycycle value keep
increasing.
@par Keywords
Timers, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
@par Directory contents
- TIM/TIM_PWMOutput/Inc/stm32wbxx_it.h Interrupt handlers header file
- TIM/TIM_PWMOutput/Inc/main.h Header for main.c module
- TIM/TIM_PWMOutput/Inc/stm32_assert.h Template file to include assert_failed function
- TIM/TIM_PWMOutput/Src/stm32wbxx_it.c Interrupt handlers
- TIM/TIM_PWMOutput/Src/main.c Main program
- TIM/TIM_PWMOutput/Src/system_stm32wbxx.c STM32WBxx system source file
@par Hardware and Software environment
- This example runs on STM32WB55xx devices.
- This example has been tested with P-NUCLEO-WB55 board and can be
easily tailored to any other supported device and development board.
- P-NUCLEO-WB55 Set-up:
- TIM2_CH1 PA.05: connected to pin 11 of CN10 connector
- LED2 PB.00: connected to pin 22 of CN10 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
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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