1、功能说明
   1) 此例程展示了CM4内核下的XSPI的基本配置方法。
   2) XSPI QUAD 模式擦除、读、写外部Nand Flash设备
   
2、使用环境

    软件开发环境：KEIL MDK-ARM V5.34
                  IAR EWARM 8.50.1 
    芯片支持：
          N32H785
          N32H785xxxEC
          N32H787

3、使用说明

    系统配置
        1、时钟源：HSI+PLL
        2、系统时钟频率：
            M7核 600MHz  M4核 300MHz
        3、打印：PB10 - baud rate 115200
        4、XSPI配置：
             时钟：系统时钟2分频；
             引脚：NSS0--PE5、CLK--PB2、IO0--PI9、IO1--PI10、IO2--PI11、IO3--PA6
             外部Spi_Flash设备：GD5F1GQ5


    使用方法：
        1、将78x的GPIO的LedBlink demo和当前CM4的工程程序分别编译后下载到开发板并复位运行;
        2、可观察到PA2间隔1s循环点亮指示CM4正在运行;
        3、XSPI 初始化完成后，先通过标准模式分别擦除两个Spi_Flash设备，然后读取确认数据是否为0xFF，有错误则打印报错，
            再通过四线模式往 NAND Flash设备写256字节，然后读取确认数据是否为写入的内容，有错误则打印报错。
        
4、注意事项
    1.需外接NandFlash。
    
1. Function description
    1) This example shows the basic configuration of GPIO in the condition of CM4.
    2) XSPI quad mode erase, read, write external Nand Flash device

2. Development environment

    Software development environment: KEIL MDK-ARM V5.34
                                      IAR EWARM 8.50.1 
    MCU support:
        N32H785
        N32H785xxxEC
        N32H787

3. How to use

    System Configuration:
        1. Clock source: HSI+PLL
        2. System Clock frequency: 
            M7 Core：600MHz  M4 Core：300MHz
        3. Printing: PB10 - baud rate 115200
        4. XSPI Configuration:
            Clock: System clock 2 divisions;
            Pin: NSS0--PE5、CLK--PB2、IO0--PI9、IO1--PI10、IO2--PI11、IO3--PA6
            External Spi_Flash device: GD5F1GQ5

     Instructions:
        1. Compile the LedBlink demo for 78x's GPIO and the current CM4 project program respectively, 
           then download them to the development board and reset to run；
        2. PA2 flashes to indicate that the M4 core is running; 
        3. After the initialization of XSPI is completed, erase the two Spi_Flash devices respectively through the standard mode, then read and confirm whether the data is 0xFF, 
            if there is any error, print an error report.
            Then Write 256 bytes to the NAND Flash device through four wire mode, and then read to confirm if the data is the written content. If there is an error, print an error message. and if there is any error, then print an error message.

4. Attention
    1.Requires an external NAND Flash。

