STM32CubeF4

@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file PWR/PWR_STANDBY/readme.txt
* @author MCD Application Team
* @brief Description of the PWR STANDBY example.
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@endverbatim

@par Example Description

How to enter the Standby mode and wake up from this mode by using an external
reset or the WKUP pin.

In the associated software, the system clock is set to 100 MHz.
The SysTick is programmed to generate an interrupt each 1 ms.

After a reset (or wake-up from STANDBY mode), LED1 is ON and MCU is in RUN mode.
The system enters STANDBY mode after 5s, LED1 is OFF.
A rising edge on wakeup pin WKUP1 PA.00 will wake-up the system from STANDBY.
Alternatively, an external RESET of the board will lead to a system wake-up as well.
The LED1 Blinks once in order to indicate the system was resumed from Standby mode.
These steps are repeated in an infinite loop.

@note This example can not be used in DEBUG mode due to the fact
that the Cortex-M4 core is no longer clocked during low power mode
so debugging features are disabled.

@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 needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.

@par Keywords

Power, PWR, Standby mode, Interrupt, EXTI, Wakeup, Low Power, External reset

@par Directory contents

- PWR/PWR_STANDBY/Inc/stm32f4xx_conf.h HAL Configuration file
- PWR/PWR_STANDBY/Inc/stm32f4xx_it.h Header for stm32f4xx_it.c
- PWR/PWR_STANDBY/Inc/main.h Header file for main.c
- PWR/PWR_STANDBY/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
- PWR/PWR_STANDBY/Src/stm32f4xx_it.c Interrupt handlers
- PWR/PWR_STANDBY/Src/main.c Main program
- PWR/PWR_STANDBY/Src/stm32f4xx_hal_msp.c HAL MSP module

@par Hardware and Software environment

- This example runs on STM32F412Zx devices

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

- NUCLEO-F412ZG Rev B Set-up
- LED1 connected to PB.00 pin.
- Put a Jumper between PA.00 and 3.3V to generate a rising edge on PWR_WAKEUP_PIN1.
- Connect an ampere-meter to JP5 to measure the IDD current.

- NUCLEO-F412ZG Rev B (not yet available) adds two solder bridges to allow
connecting the push button to either PA0 or to PC13.
The push-button still connected to PC13. It is up to the user to change the settings.

@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
- Wake-up will be done in putting 3.3V to PA.00 pin (present on pin29 of CN10).
Wired should be put between PA.00 and GND before running test. Connect to 3V3 to awake board.
- Run the example