96 lines
4.1 KiB
Plaintext
96 lines
4.1 KiB
Plaintext
/**
|
|
@page TIM_PWMInput TIM PWM Input example
|
|
|
|
@verbatim
|
|
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
|
|
* @file TIM/TIM_PWMInput/readme.txt
|
|
* @author MCD Application Team
|
|
* @brief Description of the TIM PWM_Input example.
|
|
******************************************************************************
|
|
* @attention
|
|
*
|
|
* <h2><center>© Copyright (c) 2016 STMicroelectronics.
|
|
* All rights reserved.</center></h2>
|
|
*
|
|
* 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 the TIM peripheral to measure an external signal frequency and
|
|
duty cycle.
|
|
|
|
The TIM3CLK frequency is set to SystemCoreClock/1 (Hz), the Prescaler is 0 so the
|
|
counter clock is SystemCoreClock/1 (Hz).
|
|
SystemCoreClock is set to 72 MHz for STM32F103xB Devices.
|
|
|
|
TIM3 is configured in PWM Input Mode: the external signal is connected to
|
|
TIM3 Channel2 used as input pin.
|
|
To measure the frequency and the duty cycle, we use the TIM3 CC2 interrupt request,
|
|
so in the TIM3_IRQHandler routine, the frequency and the duty cycle of the external
|
|
signal are computed.
|
|
|
|
"uwFrequency" variable contains the external signal frequency:
|
|
TIM3 counter clock = SystemCoreClock/1,
|
|
uwFrequency = TIM3 counter clock / TIM3_CCR2 in Hz,
|
|
|
|
"uwDutyCycle" variable contains the external signal duty cycle:
|
|
uwDutyCycle = (TIM3_CCR1*100)/(TIM3_CCR2) in %.
|
|
|
|
The minimum frequency value to measure is (TIM3 counter clock / CCR MAX)
|
|
= (72 MHz/1)/ 65535
|
|
= 1099 Hz
|
|
|
|
TIM2 can be used to generate the external signal in case a function generator
|
|
is not available. TIM2 is configured in PWM Output Mode to produce a square wave on PA.00.
|
|
Frequency and duty cycles can be changed by pressing the User Button (PC13).
|
|
Six combinatins are available (see thables aFrequency[] and aDutyCycle[]).
|
|
|
|
@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_PWMInput/Inc/stm32f1xx_hal_conf.h HAL configuration file
|
|
- TIM/TIM_PWMInput/Inc/stm32f1xx_it.h Interrupt handlers header file
|
|
- TIM/TIM_PWMInput/Inc/main.h Header for main.c module
|
|
- TIM/TIM_PWMInput/Src/stm32f1xx_it.c Interrupt handlers
|
|
- TIM/TIM_PWMInput/Src/main.c Main program
|
|
- TIM/TIM_PWMInput/Src/stm32f1xx_hal_msp.c HAL MSP file
|
|
- TIM/TIM_PWMInput/Src/system_stm32f1xx.c STM32F1xx system source file
|
|
|
|
|
|
@par Hardware and Software environment
|
|
|
|
- This example runs on STM32F103xB devices.
|
|
|
|
- This example has been tested with STMicroelectronics STM32F103RB-Nucleo
|
|
board and can be easily tailored to any other supported device
|
|
and development board.
|
|
|
|
- STM32F103RB-Nucleo Set-up
|
|
- You can either Connect the external signal to measure to the TIM3 CH2 pin (PA.07) (pin 4 in CN5 connector).
|
|
- Or connect TIM3 CH1 pin PA.00 (pin 1 in CN8 connector) to the TIM3 CH2 pin (PA.07) instead of an external signal.
|
|
|
|
|
|
@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>
|
|
*/
|