static void MX_MDMA_Init(void)
{
  /* MDMA controller clock enable */
  __HAL_RCC_MDMA_CLK_ENABLE();

  /* Configure MDMA channel MDMA_Channel7 */
  /* Configure MDMA request hmdma_mdma_channel7_sw_0 on MDMA_Channel7 */
  hmdma_mdma_channel7_sw_0.Instance = MDMA_Channel7;
  hmdma_mdma_channel7_sw_0.Init.Request = MDMA_REQUEST_SW;
  hmdma_mdma_channel7_sw_0.Init.TransferTriggerMode = MDMA_BLOCK_TRANSFER;
  hmdma_mdma_channel7_sw_0.Init.Priority = MDMA_PRIORITY_LOW;
  hmdma_mdma_channel7_sw_0.Init.Endianness = MDMA_LITTLE_ENDIANNESS_PRESERVE;
  hmdma_mdma_channel7_sw_0.Init.SourceInc = MDMA_SRC_INC_BYTE; //HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.DestinationInc = MDMA_DEST_INC_BYTE; //HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.SourceDataSize = MDMA_SRC_DATASIZE_BYTE; //HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.DestDataSize = MDMA_DEST_DATASIZE_BYTE; //HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.DataAlignment = MDMA_DATAALIGN_PACKENABLE;
  hmdma_mdma_channel7_sw_0.Init.BufferTransferLength = 8; //32; //1;
  hmdma_mdma_channel7_sw_0.Init.SourceBurst = MDMA_SOURCE_BURST_SINGLE;
  hmdma_mdma_channel7_sw_0.Init.DestBurst = MDMA_DEST_BURST_SINGLE;
  hmdma_mdma_channel7_sw_0.Init.SourceBlockAddressOffset = 0;
  hmdma_mdma_channel7_sw_0.Init.DestBlockAddressOffset = 0;
  if (HAL_MDMA_Init(&hmdma_mdma_channel7_sw_0) != HAL_OK)
  {
    Error_Handler();
  }

}

u8 Buffer0[32] __attribute__((at(0x30000000)));  //__attribute__((aligned(32)));
volatile u8 Buffer1[32] /*__attribute__((aligned(32)));*/   __attribute__((at(0x30040000)));        //__attribute__((aligned(32)));

int main(void)
{
SCB_EnableICache();
SCB_EnableDCache();

HAL_Init();

SystemClock_Config();

MX_GPIO_Init();

MX_MDMA_Init();

LED(RESET);

memset(       Buffer0,0,sizeof(Buffer0));
memset((void*)Buffer1,0,sizeof(Buffer1));

for(u32 i=0;i<32;i++)Buffer0[i]=0xAA;

SCB_CleanDCache(); //сбрасываем содержимое кэша данных в память

if(HAL_MDMA_Start(&hmdma_mdma_channel7_sw_0,(u32)Buffer0,(u32)Buffer1,1,1)         !=HAL_OK)while(1);

if(HAL_MDMA_PollForTransfer(&hmdma_mdma_channel7_sw_0,HAL_MDMA_BLOCK_TRANSFER,1000)!=HAL_OK)while(1);

delay_ms(500);

if(Buffer1[0]!=0xAA)
{
LED(SET);
while(1);
}

while(1)
{
LED(SET);
delay_ms(100);
LED(RESET);
delay_ms(100);
}



while(1);

if(Buffer1[0]!=0xAA)
{
LED(SET);
while(1);
}

static void MPU_Conf(void)
{
MPU_Region_InitTypeDef MPU_InitStruct;

HAL_MPU_Disable();

MPU_InitStruct.Enable=MPU_REGION_ENABLE;

MPU_InitStruct.BaseAddress = 0x30040000;
MPU_InitStruct.Size = MPU_REGION_SIZE_32KB;

MPU_InitStruct.AccessPermission=MPU_REGION_FULL_ACCESS;

MPU_InitStruct.TypeExtField=MPU_TEX_LEVEL0;

MPU_InitStruct.IsCacheable=MPU_ACCESS_CACHEABLE;
MPU_InitStruct.IsBufferable=MPU_ACCESS_BUFFERABLE;
MPU_InitStruct.IsShareable=MPU_ACCESS_SHAREABLE;

MPU_InitStruct.Number=MPU_REGION_NUMBER0;
MPU_InitStruct.SubRegionDisable=0x00;
MPU_InitStruct.DisableExec=MPU_INSTRUCTION_ACCESS_DISABLE;

HAL_MPU_ConfigRegion(&MPU_InitStruct);

HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
}

u16 Buffer[240*320] __attribute__((aligned(32)));

int main(void)
{
SCB_EnableICache();
SCB_EnableDCache();

HAL_Init();

SystemClock_Config();

MX_GPIO_Init();
MX_FMC_Init();
MX_DMA_Init();

MX_MDMA_Init();

LED(RESET);

LCD_Reset();
LCD_Init();
LCD_Position(0,0,W-1,H-1);

for(u32 i=0;i<(240*320);i++)
{
  u32 c=i/(240*40);
  Buffer[i]=  (((c/4)*0x1F)<<11) | ((((c/2)&1)*0x3F)<<5) | ((c&1)*0x1F);
}

SCB_CleanDCache();

if(HAL_MDMA_Start(&hmdma_mdma_channel7_sw_0,(u32)Buffer,(u32)&LCD_DAT32,(240*320*2)/3,3)!=HAL_OK)while(1);

if(HAL_MDMA_PollForTransfer(&hmdma_mdma_channel7_sw_0,HAL_MDMA_FULL_TRANSFER,1000)!=HAL_OK)while(1);

// SCB_InvalidateDCache();

while(1)
{
LED(SET);
delay_ms(100);
LED(RESET);
delay_ms(100);
}

static void MX_MDMA_Init(void)
{
  /* MDMA controller clock enable */
  __HAL_RCC_MDMA_CLK_ENABLE();
  /* Local variables */

  /* Configure MDMA channel MDMA_Channel7 */
  /* Configure MDMA request hmdma_mdma_channel7_sw_0 on MDMA_Channel7 */
  hmdma_mdma_channel7_sw_0.Instance = MDMA_Channel7;
  hmdma_mdma_channel7_sw_0.Init.Request = MDMA_REQUEST_SW;
  hmdma_mdma_channel7_sw_0.Init.TransferTriggerMode = MDMA_FULL_TRANSFER;
  hmdma_mdma_channel7_sw_0.Init.Priority = MDMA_PRIORITY_LOW;

  hmdma_mdma_channel7_sw_0.Init.Endianness = MDMA_LITTLE_BYTE_ENDIANNESS_EXCHANGE; //Меняем местами байты (для LCD)

  hmdma_mdma_channel7_sw_0.Init.SourceInc      = MDMA_SRC_INC_HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.DestinationInc = MDMA_DEST_INC_DISABLE;

  hmdma_mdma_channel7_sw_0.Init.SourceDataSize = MDMA_SRC_DATASIZE_HALFWORD;
  hmdma_mdma_channel7_sw_0.Init.DestDataSize = MDMA_DEST_DATASIZE_HALFWORD;

  hmdma_mdma_channel7_sw_0.Init.DataAlignment = MDMA_DATAALIGN_PACKENABLE;

  hmdma_mdma_channel7_sw_0.Init.BufferTransferLength = 2;                     //1 для BYTE, 2 для HALFWORD, 4 для WORD

  hmdma_mdma_channel7_sw_0.Init.SourceBurst = MDMA_SOURCE_BURST_SINGLE;
  hmdma_mdma_channel7_sw_0.Init.DestBurst = MDMA_DEST_BURST_SINGLE;
  hmdma_mdma_channel7_sw_0.Init.SourceBlockAddressOffset = 0;
  hmdma_mdma_channel7_sw_0.Init.DestBlockAddressOffset = 0;
  if (HAL_MDMA_Init(&hmdma_mdma_channel7_sw_0) != HAL_OK)
  {
    Error_Handler();
  }

}

вообще не смог понять