配置需要Device 或 Strongly order执行外设

== 引用硬汉嵌入式老哥的教程。==
配置参数可看我另一篇文章。
读写Cache都是关闭的，比如FMC外设驱动，扩展IO，LCD，NOR FLASH SRAM,ETH收发描述符空间
特点：保证严格按照程序代码执行
缺点：不支持非对齐访问

配置 FMC 扩展 IO 的 MPU 属性为 Device 或者 Strongly Ordered

/* 配置 FMC 扩展 IO 的 MPU 属性为 Device 或者 Strongly Ordered */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x60000000;
MPU_InitStruct.Size = ARM_MPU_REGION_SIZE_64KB;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER1;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

以太网收发描述符空间MPU配置

/* 配置以太网收发描述符部分为 Device */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x30040000;
MPU_InitStruct.Size = MPU_REGION_SIZE_256B;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER2;
MPU_InitStruct.SubRegionDisable = 0x0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

配置为最低性能NORMAL，关闭读写Cache

特点：可以像F1、F4那样使用内部SRAM。适合初学者
缺点：性能差

/* 配置 AXI SRAM 的 MPU 属性为 Write back, Read allocate， Write allocate */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x24000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_512KB;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

配置为NORMAL，此时关闭写Cache,开启读Cache（透写）

特点：SDRAM 做LCD显存和动态内存下非常方便，保证数据是直接写到显存的，开启读Cache,SDRAM 的读性能提升一倍,提升GUI性能（如LTDC）。
缺点：由于开启了读Cache，用户需要调用SCB_CleanInvalidateDCache（）函数管理数据一致性问题。只有多主控操作此空间才需要处理

    /* 配置SDRAM的MPU属性为Write through, read allocate，no write allocate */
	MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
	MPU_InitStruct.BaseAddress      = 0xC0000000;
	MPU_InitStruct.Size             = MPU_REGION_SIZE_32MB;
	MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
	MPU_InitStruct.IsBufferable     = MPU_ACCESS_NOT_BUFFERABLE;
	MPU_InitStruct.IsCacheable      = MPU_ACCESS_CACHEABLE;
	MPU_InitStruct.IsShareable      = MPU_ACCESS_NOT_SHAREABLE;
	MPU_InitStruct.Number           = MPU_REGION_NUMBER2;
	MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL0;
	MPU_InitStruct.SubRegionDisable = 0x00;
	MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_ENABLE;

配置为NORMAL 读写Cache全开，最强性能

特点：性能最强
缺点：由于读写Cache全开，用户需要调用SCB_CleanInvalidateDCache（）函数管理数据一致性问题。只有多主控操作此空间才需要处理

MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x24000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_512KB;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;