96 lines
3.8 KiB
Plaintext
96 lines
3.8 KiB
Plaintext
/**
|
|
@page TIM_PWMOutput TIM PWM Output example
|
|
|
|
@verbatim
|
|
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
|
|
* @file TIM/TIM_PWMOutput/readme.txt
|
|
* @author MCD Application Team
|
|
* @brief Description of the PWM signals generation using TIM2
|
|
******************************************************************************
|
|
* @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 72 MHz for STM32F1xx Devices.
|
|
|
|
In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1) x2,
|
|
since APB1 prescaler is set to 4 (0x100).
|
|
TIM2CLK = PCLK1*2
|
|
PCLK1 = HCLK/2
|
|
=> TIM2CLK = PCLK1*2 = (HCLK/2)*2 = HCLK = SystemCoreClock
|
|
|
|
To get TIM2 counter clock at 2.1 MHz, the prescaler is computed as follows:
|
|
Prescaler = (TIM2CLK / TIM2 counter clock) - 1
|
|
Prescaler = ((SystemCoreClock) /2.1 MHz) - 1
|
|
|
|
To get TIM2 output clock at 3 KHz, the period (ARR)) is computed as follows:
|
|
ARR = (TIM2 counter clock / TIM2 output clock) - 1
|
|
= 699
|
|
|
|
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%
|
|
|
|
|
|
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 Directory contents
|
|
|
|
- TIM/TIM_PWMOutput/Inc/stm32f1xx_hal_conf.h HAL configuration file
|
|
- TIM/TIM_PWMOutput/Inc/stm32f1xx_it.h Interrupt handlers header file
|
|
- TIM/TIM_PWMOutput/Inc/main.h Header for main.c module
|
|
- TIM/TIM_PWMOutput/Src/stm32f1xx_it.c Interrupt handlers
|
|
- TIM/TIM_PWMOutput/Src/main.c Main program
|
|
- TIM/TIM_PWMOutput/Src/stm32f1xx_hal_msp.c HAL MSP file
|
|
- TIM/TIM_PWMOutput/Src/system_stm32f1xx.c STM32F1xx system source file
|
|
|
|
|
|
@par Hardware and Software environment
|
|
|
|
- This example runs on STM32F103xG devices.
|
|
- In this example, the clock is set to 72 MHz.
|
|
|
|
- This example has been tested with STMicroelectronics STM3210E-EVAL RevD
|
|
board and can be easily tailored to any other supported device
|
|
and development board.
|
|
|
|
- STM3210E-EVAL RevD Set-up
|
|
Connect the following pins to an oscilloscope to monitor the different waveforms:
|
|
- TIM2_CH1 : PA.0 (On Eval Board, pin 31 on CN1 for example)
|
|
- TIM2_CH2 : PA.1 (On Eval Board, pin 33 on CN1 for example)
|
|
- TIM2_CH3 : PA.2 (On Eval Board, pin 34 on CN1 for example)
|
|
- TIM2_CH4 : PA.3 (On Eval Board, pin 58 on CN11 for example)
|
|
|
|
|
|
@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
|
|
|
|
|
|
*/
|