================================================================================
                                样例使用说明
                             Sample Description
================================================================================
功能描述:
此样例是利用轮询对串口外设接口（SPI）与外部设备以全双工串行方式进行通信的演示，
主设备提供通信时钟SCK，通过MOSI/MISO引脚发送/接收数据。从设备通过MOSI/MISO引脚接
收/发送数据。数据以主机提供的SCK沿同步被移位，完成全双工通信。

Function descriptions:
This sample is a demonstration of using polling to communicate with a serial 
peripheral interface (SPI) and an external device in full-duplex serial mode. 
The master device provides the communication clock SCK and sends/receives data 
through the MOSI/MISO pin. The slave device receives/transmits data through the 
MOSI/MISO pins. The data is shifted synchronously along the SCK provided by the 
master to complete full-duplex communication.
================================================================================
测试环境：
测试用板：PY32F005_STK
MDK版本： 5.28
IAR版本： 9.20
GCC 版本：GNU Arm Embedded Toolchain 10.3-2021.10

Test environment:
Test board: PY32F005_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10
================================================================================
使用步骤:
1.选择两块STK板，一块作为主机，一块作为从机
2.编译下载主机程序SPI_TwoBoards_FullDuplexMaster_Polling_Init
3.编译下载从机程序SPI_TwoBoards_FullDuplexSlave_Polling_Init
4.主机与从机引脚连接(箭头指向为信号传输方向)
主机MASTER：         从机SLAVE：
SCK(PB0)   ----->    SCK(PB0)
MISO(PB2)  <-----    MISO(PB2)
MOSI(PB3)  ----->    MOSI(PB3)
GND       <----->    GND
5.主从机上电
6.按下从机复位按键先运行从机程序，再按下主机用户按键运行主机程序
7.观察串口助手，如果主、从机串口助手均接收到“SPI transfer succeeded”则通信成功；
如果主、从机串口助手接收到“SPI Transfer Error”则通信失败。

Example execution steps:
1.Select two STK boards, one as the host and one as the slave
2.Compile and download the host program SPI_TwoBoards_FullDuplexMaster_Polling_Init
3.Compile and download the slave program SPI_TwoBoards_FullDuplexSlave_Polling_Init
4.Connect the host and slave pins as follows (the arrows point to indicate the
direction of signal transmission)
MASTER：             SLAVE：
SCK(PB0)   ----->    SCK(PB0)
MISO(PB2)  <-----    MISO(PB2)
MOSI(PB3)  ----->    MOSI(PB3)
GND       <----->    GND
5.Power on the master and slave
6.Press the slave reset button to run the slave program first, then press the
host user button to run the host program
7.Observe the serial assistant, if both master and slave serial assistant 
receive "SPI transfer succeeded", the communication is successful;
If the master and slave serial assistant receive "SPI Transfer Error",the
communication fails.
================================================================================
注意事项：

Notes:

================================================================================