1、功能说明

    该测例演示了LPUART与USARTz间通过DMA实现的基础通信。USARTz可以是USART3
或UART5。
    首先，DMA传输TxBuffer1数据至LPUART发送数据寄存器，随后数据发送至
USARTz。USARTz通过查询检查标志接收数据，存至RxBuffer2。
    同时，DMA传输TxBuffer2数据至USARTz发送数据寄存器，随后数据发送至
LPUART。LPUART利用中断接收数据，存至RxBuffer1。
    最后，分别比较两组收、发数据，比较结果存入TransferStatus1变量
和TransferStatus2变量。


2、使用环境

	软件开发环境：KEIL MDK-ARM Professional Version 5.26.2.0

        硬件环境：最小系统板N32G43XRL-STB V1.0


3、使用说明
	
    系统时钟配置如下：
    - 时钟源 = HSE + PLL
    - 系统时钟 = 108MHz
    
    LPUART配置如下：
    - 波特率 = 9600 baud
    - 字长 = 8数据位（固定）
    - 1停止位（固定）
    - 校验控制禁用
    - 硬件流控制禁用（RTS和CTS信号）
    - 接收器和发送器使能
    - DMA发送模式和DMA接收模式使能
    
    LPUART配置如下：
    - 波特率 = 9600 baud
    - 字长 = 8数据位（固定）
    - 1停止位（固定）
    - 校验控制禁用
    - 硬件流控制禁用（RTS和CTS信号）
    - 接收器和发送器使能
    - DMA发送模式和DMA接收模式使能
    
    USART引脚连接如下：
    - LPUART_Tx.PA4   <------->   USART3_Rx.PC11
    - LPUART_Rx.PA3   <------->   USART3_Tx.PC10
    或
    - LPUART_Tx.PB6    <------->   UART5_Rx.PB5
    - LPUART_Rx.PB7    <------->   UART5_Tx.PB4

    
    测试步骤与现象：
    - Demo在KEIL环境下编译后，下载至MCU
    - 复位运行，依次查看变量TransferStatus1和TransferStatus2，其中，
      PASSED为测试通过，FAILED为测试异常


4、注意事项

1. Function description

    This test example demonstrates basic communication between LPUART and USARTz via DMA. USARTz can be USART3
or UART5.
    First, the DMA transfers the TxBuffer1 data to the LPUART transmit data register, and then the data is sent to
USARTz. USARTz receives data by polling the check flag and store it in RxBuffer2.
    At the same time, the DMA transfers the TxBuffer2 data to the USARTz transmit data register, and then the data is sent to
LPUART. The LPUART uses the interrupt to receive data and stores it in RxBuffer1.
    Finally, compare the two groups of receiving and sending data respectively, and store the comparison results in the TransferStatus1 variable
and the TransferStatus2 variable.


2. Use environment

Software development environment: KEIL MDK-ARM Professional Version 5.26.2.0

        Hardware environment: minimum system board N32G43XRL-STB V1.0


3. Instructions for use

    The system clock configuration is as follows:
    - Clock source = HSE + PLL
    - System Clock = 108MHz
    
    The LPUART configuration is as follows:
    - Baud rate = 9600 baud
    - Word length = 8 data bits (fixed)
    - 1 stop bit (fixed)
    - checksum control disabled
    - Hardware flow control disabled (RTS and CTS signals)
    - Receiver and transmitter enable
    - DMA transmit mode and DMA receive mode enable
    
    The LPUART configuration is as follows:
    - Baud rate = 9600 baud
    - Word length = 8 data bits (fixed)
    - 1 stop bit (fixed)
    - checksum control disabled
    - Hardware flow control disabled (RTS and CTS signals)
    - Receiver and transmitter enable
    - DMA transmit mode and DMA receive mode enable
    
    The USART pins are connected as follows:
    - LPUART_Tx.PA4 <-------> USART3_Rx.PC11
    - LPUART_Rx.PA3 <-------> USART3_Tx.PC10
    or
    - LPUART_Tx.PB6 <-------> UART5_Rx.PB5
    - LPUART_Rx.PB7 <-------> UART5_Tx.PB4

    
    Test steps and phenomena:
    - Demo is compiled in KEIL environment and downloaded to MCU
    - Reset operation, check the variables TransferStatus1 and TransferStatus2 in turn, where,
      PASSED is the test passed, FAILED is the test abnormal


4. Attention