/**
  ******************************************************************************
  * 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:
--------------------------------------------------------------------------------->
2019-07-17	V1.0.0	AE TEAM


<--------------------------------------------------------------------------------
Demo introduction:
--------------------------------------------------------------------------------->
SPI主机中断方式数据收发。主机发送数组send_buf中的8个数据给从机，并接收从机的8个数据存入recv_buf。

<--------------------------------------------------------------------------------
System clock:
--------------------------------------------------------------------------------->
External HOSC[32MHz] divided by 32, then PLL to 48Mhz.

<--------------------------------------------------------------------------------
Pin connection: 
--------------------------------------------------------------------------------->
SPI1_CS   ---- PA5[GPIO_FUNC_1]
SPI1_SCK  ---- PA4[GPIO_FUNC_4]
SPI1_MISO ---- PA6[GPIO_FUNC_4]
SPI1_MOSI ---- PA7[GPIO_FUNC_4]