/**
  @page UART_HyperTerminal_DMA UART Hyperterminal DMA Example
  
  @verbatim
  ******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
  * @file    UART/UART_HyperTerminal_DMA/readme.txt 
  * @author  MCD Application Team
  * @version V1.5.0
  * @date    14-April-2017
  * @brief   Description of the UART Hyperterminal example.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

This example shows how to ensure UART Data buffer transmission and reception with 
DMA. The communication is done with the Hyperterminal PC application.

Board: STM32VL-Discovery
Tx Pin: PA.09
Rx Pin: PA.10
   _________________________ 
  |           ______________|                       _______________
  |          |USART         |                      | HyperTerminal |
  |          |              |                      |               |
  |          |           TX |______________________|RX             |
  |          |              |                      |               |
  |          |              |     RS232 Cable      |               |             
  |          |              |                      |               |
  |          |           RX |______________________|TX             |          
  |          |              |                      |               |           
  |          |______________|                      |_______________|          
  |                         |                       
  |                         |                    
  |                         |                      
  |                         |                      
  |_STM32_Board_____________|                      

At the beginning of the main program the HAL_Init() function is called to reset 
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 24 MHz.

The UART peripheral configuration is ensured by the HAL_UART_Init() function.
This later is calling the HAL_UART_MspInit()function which core is implementing
the configuration of the needed UART resources according to the used hardware (CLOCK, 
GPIO, DMA and NVIC). You may update this function to change UART configuration.

The UART/Hyperterminal communication is then initiated.
The HAL_UART_Receive_DMA() and the HAL_UART_Transmit_DMA() functions allow respectively 
the reception of Data from Hyperterminal and the transmission of a predefined data 
buffer.

The Asynchronous communication aspect of the UART is clearly highlighted as the  
data buffers transmission/reception to/from Hyperterminal are done simultaneously.

For this example the TxBuffer is predefined and the RxBuffer size is limited to 
10 data by the mean of the RXBUFFERSIZE define in the main.c file.

In a first step the received data will be stored in the RxBuffer buffer and the 
TxBuffer buffer content will be displayed in the Hyperterminal interface.
In a second step the received data in the RxBuffer buffer will be sent back to 
Hyperterminal and displayed.
The end of this two steps are monitored through the HAL_UART_GetState() function
result.

STM32 board's LEDs can be used to monitor the transfer status:
 - LED3 turns ON when the transmission process is complete.
 - LED4 turns ON if transmission/reception is complete and OK.
 - LED4 turns OFF when there is an error in transmission/reception process (HAL_UART_ErrorCallback is called).
 - LED4 toggles when there another error is detected.  

The UART is configured as follows:
    - BaudRate = 9600 baud  
    - Word Length = 8 Bits (7 data bit + 1 parity bit)
    - One Stop Bit
    - Odd parity
    - Hardware flow control disabled (RTS and CTS signals)
    - Reception and transmission are enabled in the time

@note USARTx/UARTx instance used and associated resources can be updated in "main.h"
file depending hardware configuration used.

@note When the parity is enabled, the computed parity is inserted at the MSB
position of the transmitted data.


@par Directory contents 

  - UART/UART_HyperTerminal_DMA/Inc/stm32f1xx_hal_conf.h    HAL configuration file
  - UART/UART_HyperTerminal_DMA/Inc/stm32f1xx_it.h          DMA interrupt handlers header file
  - UART/UART_HyperTerminal_DMA/Inc/main.h                  Header for main.c module  
  - UART/UART_HyperTerminal_DMA/Src/stm32f1xx_it.c          DMA interrupt handlers
  - UART/UART_HyperTerminal_DMA/Src/main.c                  Main program
  - UART/UART_HyperTerminal_DMA/Src/stm32f1xx_hal_msp.c     HAL MSP module
  - UART/UART_HyperTerminal_DMA/Src/system_stm32f1xx.c      STM32F1xx system source file


@par Hardware and Software environment

  - This example runs on STM32F100xB devices.
    
  - This example has been tested with STM32VL-Discovery board and can be
    easily tailored to any other supported device and development board.    

  - STM32_VL_DISCOVERY Set-up
    - Connect USART1 TX (PA9) to RX pin of PC serial port (or USB to UART adapter)
      and USART1 RX (PA10) to TX pin of PC serial port.

  - Hyperterminal configuration:
    - Word Length = 7 Bits
    - One Stop Bit
    - Odd parity
    - BaudRate = 9600 baud
    - flow control: None 

@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


 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */
