GPIO IO Toggle example

  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    GPIO/GPIO_IOToggle/readme.txt  
  * @author  MCD Application Team
  * @version V1.4.0
  * @date    24-July-2014
  * @brief   GPIO IO Toggle example Description.
  ******************************************************************************
  *
  * 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

GPIO ports are connected on AHB bus, using BSRR and BRR registers two cycles are required to set a pin and another two cycles to reset it. So GPIO pins can toggle at AHB clock divided by 4.

This example describes how to use BSRR and BRR (Port Bit Set/Reset Register High and Low) for maximum IO toggling.

PC10 and PC11 when using the STM320518-EVAL (configured in output pushpull mode) toggles in a forever loop:

• Set PC10 and PC11 by setting corresponding bits in BSRR register
• Reset PC10 and PC11 by setting corresponding bits in BRR register

In this example, HCLK is configured at 48 MHz so PC10 and PC11 toggles at 12MHz. To achieve the maximum IO toggling frequency, you have to configure your compiler options for high speed optimization.

Directory contents

• GPIO/GPIO_IOToggle/stm32f0xx_conf.h Library Configuration file
• GPIO/GPIO_IOToggle/stm32f0xx_it.c Interrupt handlers
• GPIO/GPIO_IOToggle/stm32f0xx_it.h Interrupt handlers header file
• GPIO/GPIO_IOToggle/main.c Main program
  • GPIO/GPIO_IOToggle/main.h Main program header file
• GPIO/GPIO_IOToggle/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 boardd.

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
• Rebuild all files and load your image into target memory
• Run the example

© COPYRIGHT STMicroelectronics