/**
  ******************************************************************************
  * 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.
  *
  * Copyright (C) Shanghai Eastsoft Microelectronics Co., Ltd. ALL rights reserved.
  *******************************************************************************
  */

<--------------------------------------------------------------------------------
Version history:
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2019-07-17	V1.0.0	AE TEAM


<--------------------------------------------------------------------------------
Demo introduction:
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Transmit/Receive data using SPI by duplex dma mode.

<--------------------------------------------------------------------------------
System clock:
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Internal HRC[24MHz] divided by 6, then PLL to 48MHz.

<--------------------------------------------------------------------------------
Pin connection: 
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SPI0_CS   ---- (PA4, GPIO_FUNC_1)
SPI0_SCK  ---- (PA5, GPIO_FUNC_6)
SPI0_MISO ---- (PA6, GPIO_FUNC_6)
SPI0_MOSI ---- (PA7, GPIO_FUNC_6)