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/**
@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 TIM2
******************************************************************************
*
* Copyright (c) 2019-2021 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.
At the beginning of the main program the HAL_Init() function is called to reset
all the peripherals, initialize the Flash interface and the systick.
The SystemClock_Config() function is used to configure the system clock for STM32WB15CCUx Devices :
The CPU at 64 MHz
SystemCoreClock is set to 64 MHz for STM32WBxx Devices.
In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1),
since APB1 prescaler is equal to 1.
TIM2CLK = PCLK1
PCLK1 = HCLK
=> TIM2CLK = HCLK = SystemCoreClock
To get TIM2 counter clock at 1 MHz, the prescaler is computed as follows:
Prescaler = (TIM2CLK / TIM2 counter clock) - 1
Prescaler = ((SystemCoreClock) /1 MHz) - 1
To get TIM2 output clock at 24 KHz, the period (ARR)) is computed as follows:
ARR = (TIM2 counter clock / TIM2 output clock) - 1
= 40
TIM2 Channel1 duty cycle = (TIM2_CCR1/ TIM2_ARR + 1)* 100 = 50%
TIM2 Channel2 duty cycle = (TIM2_CCR2/ TIM2_ARR + 1)* 100 = 37.5%
TIM2 Channel3 duty cycle = (TIM2_CCR3/ TIM2_ARR + 1)* 100 = 25%
TIM2 Channel4 duty cycle = (TIM2_CCR4/ TIM2_ARR + 1)* 100 = 12.5%
LED3 is ON when there are an error.
The PWM waveforms can be displayed using an oscilloscope.
@note The duty cycles values mentioned above are theoretical (obtained when the system clock frequency is exactly 64 MHz).
They might be slightly different depending on system clock frequency precision.
@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 This example needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Timer, Output, signal, PWM, Oscilloscope, Frequency, Duty cycle, Waveform
@par Directory contents
- TIM/TIM_PWMOutput/Inc/nucleo_wb15cc_conf.h BSP configuration file
- TIM/TIM_PWMOutput/Inc/stm32wbxx_hal_conf.h HAL configuration file
- 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/Src/stm32wbxx_it.c Interrupt handlers
- TIM/TIM_PWMOutput/Src/main.c Main program
- TIM/TIM_PWMOutput/Src/stm32wbxx_hal_msp.c HAL MSP file
- TIM/TIM_PWMOutput/Src/system_stm32wbxx.c STM32WBxx system source file
@par Hardware and Software environment
- This example runs on STM32WB15CCUx devices.
- In this example, the clock is set to 64 MHz.
- This example has been tested with STMicroelectronics NUCLEO-WB15CC
board and can be easily tailored to any other supported device
and development board.
- NUCLEO-WB15CC Set-up
Connect the following pins to an oscilloscope to monitor the different waveforms:
- TIM2_CH1 : PA.00 (pin 34 in CN7 connector)
- TIM2_CH2 : PA.01 (pin 32 in CN7 connector)
- TIM2_CH3 : PA.02 (pin 36 in CN7 connector)
- TIM2_CH4 : PA.03 (pin 38 in CN7 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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