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                                样例使用说明
                                Sample Description
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功能描述：
此样例是对I2S主机与I2S从机以DMA方式进行通信的演示，I2S主机先向I2S从机发送数据
0x1~0x10，I2S从机接收到数据后，再向I2S主机回发数据0x1~0x10，当I2S主机和I2S从机
成功接收数据时，小灯处于常亮状态；否则小灯处于闪烁状态。

Function descriptions:
This sample demonstrates communication between the I2S master and I2S slave 
using DMA. The I2S master sends data 0x1 to 0x10 to the I2S slave. The I2S 
slave receives the data and sends back data 0x1 to 0x10 to the I2S master. 
When both the I2S master and I2S slave successfully receive the data, the 
LED will be constantly on. Otherwise, the LED will be blinking.
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测试环境：
测试用板：PY32F032_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: PY32F032_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10
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使用步骤:
1. 选择两块 STK 板，一块作为主机，一块作为从机。
2.打开"#define BOARD_IN_MASTER_MODE"宏定义，编译程序下载到主机。
3.屏蔽"#define BOARD_IN_MASTER_MODE"宏定义，编译程序下载到从机。
4. 连接主机和从机的引脚（箭头指向为信号传输方向）：
   主机 MASTER:        从机 SLAVE:
   WS(PA4)    ----->   WS(PA4)
   CK(PA5)    ----->   CK(PA5)
   SD(PA7)    <---->   SD(PA7)
   GND        <---->   GND
5. 主机和从机上电后，按下主机和从机的复位按键。
6. 先按下从机的用户按键运行从机程序，再按下主机的用户按键运行主机程序。
7. 观察主机和从机的 LED 灯，当主机和从机的 LED 灯由常暗转为常亮状态，则表示主机和从机
   收发数据成功；当主机或从机的 LED 灯处于闪烁状态，则表示主机和从机收发数据失败。

Example execution steps:
1. Select two STK boards, one as the master and one as the slave.
2. Open the “#define BOARD_IN_MASTER_MODE” macro definition, compile the program 
   to download to the host.
3. Mask “#define BOARD_IN_MASTER_MODE” macro definition, compile the program to 
   download to the slave.
4. Connect the pins of the master and slave boards (direction indicated by the 
   arrow):
   Master MASTER:      Slave SLAVE:
   WS(PA4)    ----->   WS(PA4)
   CK(PA5)    ----->   CK(PA5)
   SD(PA7)    <---->   SD(PA7)
   GND        <---->   GND
5. Power on the master and slave boards, and press the reset buttons on both.
6. Press the user button on the slave to run the slave program first, then press 
   the user button on the master to run the master program.
7. Observe the LEDs on the master and slave boards. When the LEDs on both the 
   master and slave boards change from dim to constantly on, it indicates that 
   the master and slave have successfully transmitted and received data. If the 
   LEDs on the master or slave are blinking, it indicates a failure in data 
   transmission.
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注意事项:

Note:
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