TIM Time Base Description

  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    TIM/TIM_TimeBase/readme.txt 
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   Description of Time Base 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
  *
  * 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
  * limitations under the License.
  *
  ******************************************************************************
   

Example Description

This example shows how to configure the TIM peripheral in Output Compare Timing mode with the corresponding Interrupt requests for each channel in order to generate 4 different time bases.

The TIM3CLK frequency is set to SystemCoreClock (Hz), to get TIM3 counter clock at 6 MHz so the Prescaler is computed as following:

• Prescaler = (TIM3CLK / TIM3 counter clock) - 1

SystemCoreClock is set to 48MHz.

The TIM3 CC1 register value is equal to 40961, CC1 update rate = TIM3 counter clock / CCR1_Val = 146.48 Hz, so the TIM3 Channel 1 generates an interrupt each 6.8ms

The TIM3 CC2 register is equal to 27309, CC2 update rate = TIM3 counter clock / CCR2_Val = 219.7 Hz so the TIM3 Channel 2 generates an interrupt each 4.55ms

The TIM3 CC3 register is equal to 13654, CC3 update rate = TIM3 counter clock / CCR3_Val = 439.4Hz so the TIM3 Channel 3 generates an interrupt each 2.27ms

The TIM3 CC4 register is equal to 6826, CC4 update rate = TIM3 counter clock / CCR4_Val = 878.9 Hz so the TIM3 Channel 4 generates an interrupt each 1.13ms.

When the counter value reaches the Output compare registers values, the Output Compare interrupts are generated and, in the handler routine, 4 leds (LED1, LED2, LED3 and LED4) are toggled with the following frequencies:

• LED1: 73.24Hz (CC1)
• LED2: 109.8Hz (CC2)
• LED3: 219.7Hz (CC3)
• LED4: 439.4Hz (CC4)

Directory contents

• TIM/TIM_TimeBase/stm32f0xx_conf.h Library Configuration file
• TIM/TIM_TimeBase/stm32f0xx_it.c Interrupt handlers
• TIM/TIM_TimeBase/stm32f0xx_it.h Interrupt handlers header file
• TIM/TIM_TimeBase/main.c Main program
• TIM/TIM_TimeBase/main.h Header for main.c module
• TIM/TIM_TimeBase/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
  • Use LED1, LED2, LED3 and LED4 connected respectively to PC.10, PC.11, PC.12 and PD.02 pins and connect them on an oscilloscope to show the different Time Base signals.
• STM32072B-EVAL Set-up
  • Use LED1, LED2, LED3 and LED4 connected respectively to PD.08, PD.09, PD.10 and PD.11 pins and connect them on an oscilloscope to show the different Time Base signals.

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
• If the used device is STM32F051R8T6 choose STM32F051 project
  • Add the following files to the project source list
    • Utilities\STM32_EVAL\STM320518_EVAL\stm320518_eval.c
• If the used device is STM32F072VBT6 choose STM32F072 project
  • Add the following files to the project source list
    • Utilities\STM32_EVAL\STM32072B_EVAL\stm32072b_eval.c
• Rebuild all files and load your image into target memory
• Run the example

© COPYRIGHT STMicroelectronics