/**
  @page NVIC_DMA_WFIMode NVIC DMA in WFI mode example
  
  @verbatim
  ******************** (C) COPYRIGHT 2012 STMicroelectronics *******************
  * @file    NVIC/NVIC_DMA_WFIMode/readme.txt 
  * @author  MCD Application Team
  * @version V1.1.1
  * @date    13-April-2012
  * @brief   Description of the NVIC DMA in WFI mode 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.
  *
  ******************************************************************************
   @endverbatim

@par Example Description 

This example shows how to enter the system to WFI mode with DMA transfer enabled
and wake-up from this mode by the DMA End of Transfer interrupt.

In the associated software, the system clock is set to 32 MHz, the DMA1 Channel6 when using the
STM32L152-EVAL or ADC channel5 when using the STM32L152D-EVAL is configured to transfer 10 data 
from the EVAL COM1 USART data register to a predefined buffer, DST_Buffer, and to generate
an interrupt at the end of the transfer.

The EVAL COM1 USART receives data from Hyperterminal.
A LED1 is toggled with a frequency depending on the system clock, this is used 
to indicate whether the MCU is in WFI or RUN mode. 

Pressing key push button (generates rising edge on EXTI0) will put the core in
the WFI mode, causing the led pin to stop toggling.
To wake-up from WFI mode you have to send the sequence (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
from the Hyperterminal to the EVAL COM1 USART. These bytes will be transferred 
by the DMA from the EVAL COM1 receive data register to the predefined buffer, 
then generates an interrupt which exits the system from WFI mode. 
The LED1 restarts toggling and a LED2 will toggle if the buffer is correctly 
received else a LED3 is toggled.

@par Directory contents 

  - NVIC/DMA_WFIMode/stm32l1xx_conf.h    Library Configuration file
  - NVIC/DMA_WFIMode/stm32l1xx_it.c      Interrupt handlers
  - NVIC/DMA_WFIMode/stm32l1xx_it.h      Interrupt handlers header file
  - NVIC/DMA_WFIMode/main.c              Main program
  - NVIC/DMA_WFIMode/system_stm32l1xx.c  STM32L1xx system source file
  
@note The "system_stm32l1xx.c" is generated by an automatic clock configuration 
      system and can be easily customized to your own configuration. 
      To select different clock setup, use the "STM32L1xx_Clock_Configuration_V1.1.0.xls" 
      provided with the AN3309 package available on <a href="http://www.st.com/internet/mcu/family/141.jsp">  ST Microcontrollers </a>
         
@par Hardware and Software environment

  - This example runs on STM32L1xx Ultra Low Power High-, Medium-Density and Medium-Density Plus Devices.
  
  - This example has been tested with STMicroelectronics STM32L152D-EVAL (STM32L1xx 
    Ultra Low Power High-Density) and STM32L152-EVAL (STM32L1xx Ultra Low 
    Power Medium-Density) evaluation board and can be easily tailored to any 
    other supported device and development board.

  - STM32L152-EVAL Set-up
    - Use LED1, LED2 and LED3 leds connected respectively to PD.00, PD.01
      and PD.04 pins.
    - The USART2 signals (Rx, Tx) must be connected to a DB9 connector using a RS232
      transceiver.
    - Connect a null-modem female/female RS232 cable between the DB9 connector, 
      CN2 on STM32L152-EVAL board, and PC serial port.   
    - Hyperterminal configuration:
       - Word Length = 8 Bits
       - One Stop Bit
       - No parity
       - BaudRate = 115200 baud
       - flow control: None   
    - Use the Key push-button connected to pin PA0 (EXTI Line0).
    - Make sure that JP5 is on position 2<->3.


  - STM32L152D-EVAL Set-up
    - Use LED1, LED2, LED3 and LED4 leds connected respectively to PD.03, PD.07, PG.14
      and PG.15 pins
    - The USART1 signals (Rx, Tx) must be connected to a DB9, CN1 connector using a RS232
      transceiver.
    - Connect a null-modem female/female RS232 cable between the DB9 connector, 
      CN1 on STM32L152-EVAL board, and PC serial port.   
    - Hyperterminal configuration:
       - Word Length = 8 Bits
       - One Stop Bit
       - No parity
       - BaudRate = 115200 baud
       - flow control: None   
    - Use the Key push-button connected to pin PA0 (EXTI Line0).
    - Make sure that JP4 is on position 2<->3.

      
@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\STM32L1xx_StdPeriph_Templates
 - Open your preferred toolchain 
 - Rebuild all files and load your image into target memory
 - Run the example

@note
- Ultra Low Power Medium-density devices are STM32L151xx and STM32L152xx 
  microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
- Ultra Low Power Medium-density Plus devices are STM32L151xx, STM32L152xx and 
  STM32L162xx microcontrollers where the Flash memory density is 256 Kbytes.
- Ultra Low Power High-density devices are STM32L151xx, STM32L152xx and STM32L162xx 
  microcontrollers where the Flash memory density is 384 Kbytes.
    
 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */


