1、功能说明

    该测例演示了USARTy与USARTz间通过DMA（查询）实现的基础通信。USARTy和
USARTz可以是USART1和USART2。
    首先，DMA传输TxBuffer1数据至USARTy发送数据寄存器，随后数据发送至
USARTz。USARTz接收数据，DMA从USARTz接收数据寄存器搬移数据至RxBuffer2。
比较收、发数据，比较结果存入TransferStatus2变量。
    同时，DMA传输TxBuffer2数据至USARTz发送数据寄存器，随后数据发送至
USARTy。USARTy接收数据，DMA从LPUART接收数据寄存器搬移数据至RxBuffer1。
比较收、发数据，比较结果存入TransferStatus1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N32G030C8L7-STB V1.0


3、使用说明
	
    系统时钟配置如下：
    - 时钟源 = HSI + PLL
    - 系统时钟 = 48MHz
    
    USART配置如下：
    - 波特率 = 115200 baud
    - 字长 = 8数据位
    - 1停止位
    - 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：
    - USART1_Tx.PA9    <------->   USART2_Rx.PA3
    - USART1_Rx.PA10   <------->   USART2_Tx.PA2

    
    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

    需先将开发板NS-LINK的MCU_TX和MCU_RX跳线帽断开

1. Function description

    This test example demonstrates the basic communication between USARTy and USARTz through DMA (interrupt). USARTy and USARTz can be USART1 and USART2.
    First, DMA transfers the TxBuffer1 data to the USARTy send data register. After the transfer is completed, a DMA interrupt is generated, and then the data is sent to 
USARTz. USARTz receives data, DMA moves data from USARTz receive data register to RxBuffer2, and generates DMA interrupt after completion.
    At the same time, DMA transfers TxBuffer2 data to the USARTz send data register, the transfer is completed and a DMA interrupt is generated, and then the data is 
sent to LPUART. USARTy receives data, DMA moves the data from the LPUART receive data register to RxBuffer1, and generates a DMA interrupt after completion.
    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 N32G030C8L7-STB V1.0


3. Instructions for use

    The system clock configuration is as follows:
    -Clock source = HSI + PLL
    -System clock = 48MHz
    
    The USART configuration is as follows:
    -Baud rate = 115200 baud
    -Word length = 8 data bits
    -1 stop bit
    -Verification control disabled
    -Hardware flow control disabled (RTS and CTS signals)
    -Receiver and transmitter enable
    -DMA transmission mode is enabled, DMA reception mode is disabled
    
    The USART pin connections are as follows:
    -USART1_Tx.PA9 <-------> USART2_Rx.PA3
    -USART1_Rx.PA10 <-------> USART2_Tx.PA2

    
    Test steps and phenomena:
    -After the Demo is compiled in the KEIL environment, download it to the MCU
    -Reset operation, check the variables TransferStatus1 and TransferStatus2 in turn, among them,
      PASSED means the test passed, FAILED means the test is abnormal


4. Matters needing attention

    the MCU_TX and MCU_RX jumper cap of the development board NS-LINK needs to be disconnected first