/**
  @page GPIO_IOToggle GPIO IO Toggle example
  
  @verbatim
  ******************** (C) COPYRIGHT 2011 STMicroelectronics *******************
  * @file    GPIO/IOToggle/readme.txt 
  * @author  MCD Application Team
  * @version V3.5.0
  * @date    08-April-2011
  * @brief   Description of the GPIO IO Toggle example.
  ******************************************************************************
  * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
  * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
  * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
  * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
  * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
  * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
  ******************************************************************************
   @endverbatim

@par Example Description 

GPIO ports are connected on APB2 bus, using BSRRH and BSRRL registers 2 cycles 
are required to set a pin and another cycle 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
and Port Bit Reset Register) for maximum IO toggling.

PD0 and PD2 (configured in output pushpull mode) toggles in a forever loop:
 - Set PD0 and PD2 by setting corresponding bits in BSRR register
 - Reset PD0 and PD2 by setting corresponding bits in BRR register

In this example, HCLK is configured at 72 MHz so PD0 and PD2 toggles at 18MHz.
To achieve the maximum IO toggling frequency, you have to configure your compiler
options for high speed optimization.

@par Directory contents 

  - GPIO/IOToggle/stm32f10x_conf.h     Library Configuration file
  - GPIO/IOToggle/stm32f10x_it.c       Interrupt handlers
  - GPIO/IOToggle/stm32f10x_it.h       Header for stm32f10x_it.c
  - GPIO/IOToggle/main.c               Main program
  - GPIO/IOToggle/system_stm32f10x.c   STM32F10x system source file
  
@par Hardware and Software environment 

  - This example runs on STM32F10x Connectivity line, High-Density, High-Density 
    Value line, Medium-Density, XL-Density, Medium-Density Value line, Low-Density 
    and Low-Density Value line Devices.
  
  - This example has been tested with STMicroelectronics STM32100E-EVAL (High-Density
    Value line), STM32100B-EVAL (Medium-Density Value line), STM3210C-EVAL
    (Connectivity line), STM3210E-EVAL (High-Density and XL-Density) and 
    STM3210B-EVAL (Medium-Density) evaluation boards and can be easily tailored 
    to any other supported device and development board.
    To select the STMicroelectronics evaluation board used to run the example, 
    uncomment the corresponding line in stm32_eval.h file (under Utilities\STM32_EVAL)

@par 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\STM32F10x_StdPeriph_Template
 - Open your preferred toolchain 
 - Rebuild all files and load your image into target memory
 - Run the example

@note
 - Low-density Value line devices are STM32F100xx microcontrollers where the 
   Flash memory density ranges between 16 and 32 Kbytes.
 - Low-density devices are STM32F101xx, STM32F102xx and STM32F103xx 
   microcontrollers where the Flash memory density ranges between 16 and 32 Kbytes.
 - Medium-density Value line devices are STM32F100xx microcontrollers where
   the Flash memory density ranges between 64 and 128 Kbytes.  
 - Medium-density devices are STM32F101xx, STM32F102xx and STM32F103xx 
   microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
 - High-density Value line devices are STM32F100xx microcontrollers where
   the Flash memory density ranges between 256 and 512 Kbytes. 
 - High-density devices are STM32F101xx and STM32F103xx microcontrollers where
   the Flash memory density ranges between 256 and 512 Kbytes.  
 - XL-density devices are STM32F101xx and STM32F103xx microcontrollers where
   the Flash memory density ranges between 512 and 1024 Kbytes.
 - Connectivity line devices are STM32F105xx and STM32F107xx microcontrollers.
   
 * <h3><center>&copy; COPYRIGHT 2011 STMicroelectronics</center></h3>
 */
