STM32CubeF4

@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file GPIO/GPIO_IOToggle/readme.txt
* @author MCD Application Team
* @brief Description of the GPIO IO Toggle example.
******************************************************************************
* @attention
*
* Copyright (c) 2017 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
@endverbatim

@par Example Description

How to configure and use GPIOs through the HAL API.

PB.00, PB.07 and PB.14 IOs (configured in output pushpull mode) toggle in a forever loop.
On NUCLEO-F412ZG Rev B board these IOs are connected to LED1, LED2 and LED3.

In this example, HCLK is configured at 100 MHz.

@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 Keywords

System, GPIO, Output, Alternate function, Push-pull, Toggle

@par Directory contents

- GPIO/GPIO_IOToggle/Inc/stm32f4xx_hal_conf.h HAL configuration file
- GPIO/GPIO_IOToggle/Inc/stm32f4xx_it.h Interrupt handlers header file
- GPIO/GPIO_IOToggle/Inc/main.h Header for main.c module
- GPIO/GPIO_IOToggle/Src/stm32f4xx_it.c Interrupt handlers
- GPIO/GPIO_IOToggle/Src/main.c Main program
- GPIO/GPIO_IOToggle/Src/system_stm32f4xx.c STM32F4xx system source file

@par Hardware and Software environment

- This example runs on STM32F412Zx devices.

- This example has been tested with NUCLEO-F412ZG Rev B board and can be
easily tailored to any other supported device and development board.

@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