STM32F0xx Standard Peripherals Firmware Library: TIM_PWM_Input

  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    TIM/TIM_PWMInput/readme.txt 
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   Description of the TIM PWM_Input example.
  ******************************************************************************
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
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  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
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  ******************************************************************************
   

Example Description

This example shows how to use the TIM peripheral to measure the frequency and duty cycle of an external signal.

The TIM2 Clock frequency is set to SystemCoreClock(Hz), the Prescaler is 0 so the counter clock is SystemCoreClock(Hz). SystemCoreClock is set to 48 MHz in this example.

TIM2 is configured in PWM Input Mode: the external signal is connected to TIM2 Channel2 used as input pin.

To measure the frequency and the duty cycle we use the TIM2 CC2 interrupt request, so In the TIM2_IRQHandler routine, the frequency and the duty cycle of the external signal are computed.

The "Frequency" variable contains the external signal frequency: TIM2 counter clock = SystemCoreClock Frequency = TIM2 counter clock / TIM2_CCR2 in Hz

The "DutyCycle" variable contains the external signal duty cycle: DutyCycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.

The minimum frequency value to measure is 733 Hz (TIM2 counter clock / CCR MAX).

Directory contents

• TIM/TIM_PWMInput/stm32f0xx_conf.h Library Configuration file
• TIM/TIM_PWMInput/stm32f0xx_it.c Interrupt handlers
• TIM/TIM_PWMInput/stm32f0xx_it.h Interrupt handlers header file
• TIM/TIM_PWMInput/main.c Main program
• TIM/TIM_PWMInput/main.h Header for main.c module
• TIM/TIM_PWMInput/system_stm32f0xx.c STM32F0xx system source file

Note:

The "system_stm32f0xx.c" is generated by an automatic clock configuration tool and can be easily customized to meet user application requirements. To select different clock setup, use the "STM32F0xx_Clock_Configuration_VX.Y.Z.xls" provided with the AN4055 package available on ST Microcontrollers

Hardware and Software environment

• This example runs on STM32F0xx devices.

• This example has been tested with STMicroelectronics STM320518-EVAL and STM32072B-EVAL including respectively STM32F051R8T6 and STM32F072VBT6 devices and can be easily tailored to any other supported device and development board

• STM320518-EVAL Set-up
  • Connect the external signal to the TIM2 CH2 pin (PA.01) to measure the frequency and duty cycle
• STM32072B-EVAL Set-up
  • Connect the external signal to the TIM2 CH2 pin (PA.01) to measure the frequency and duty cycle

How to use it ?

In order to make the program work, you must do the following :

• Copy all source files from this example folder to the template folder under Project
• Open your preferred toolchain
• Select the appropriate workspace
• Rebuild all files and load your image into target memory
• Run the example

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