DMA: Memory to Memory

In this program, DMA is configured to transfer data in memory-to-memory mode, Data stored on Flash memory will be transferred to RAM memory. Using channel 1, data size is 32 bits therefore “Word” size must be configured and the address incremental to shift all the buffer.

#include "bsp.h"
#include <stdio.h>

extern void initialise_monitor_handles(void);

#define BUFFER_SIZE 32 

DMA_HandleTypeDef DMAHandler;
/*this variable stored in RAM will be used as detinations*/
static uint32_t Buffer[BUFFER_SIZE];
/*this variable stored in FLASH will be used as source*/
static const uint32_t DataSource[BUFFER_SIZE] =
{
  0x01020304, 0x05060708, 0x090A0B0C, 0x0D0E0F10,
  0x11121314, 0x15161718, 0x191A1B1C, 0x1D1E1F20,
  0x21222324, 0x25262728, 0x292A2B2C, 0x2D2E2F30,
  0x31323334, 0x35363738, 0x393A3B3C, 0x3D3E3F40,
  0x41424344, 0x45464748, 0x494A4B4C, 0x4D4E4F50,
  0x51525354, 0x55565758, 0x595A5B5C, 0x5D5E5F60,
  0x61626364, 0x65666768, 0x696A6B6C, 0x6D6E6F70,
  0x71727374, 0x75767778, 0x797A7B7C, 0x7D7E7F80
};

int main(void)
{
    /*Initialize HAL library*/
    HAL_Init();

    /*Activation of semihosting*/
    initialise_monitor_handles();
    printf("Hola semihosting\n\r");

    /* DMA controller clock enable */
    __HAL_RCC_DMA1_CLK_ENABLE();

    /* Configure DMA request hdma_memtomem_dma1_channel1 on DMA1_Channel1 */
    DMAHandler.Instance         = DMA1_Channel1;                /*DMA1 channel 1*/
    DMAHandler.Init.Request     = DMA_REQUEST_MEM2MEM;          /*memory to memory transfer*/
    DMAHandler.Init.Direction   = DMA_MEMORY_TO_MEMORY;         /*memory to memory transfer direction (flash to ram)*/
    DMAHandler.Init.PeriphInc   = DMA_PINC_ENABLE;              /*increment source address (flash memory)*/
    DMAHandler.Init.MemInc      = DMA_MINC_ENABLE;              /*increment destination address (ram memory)*/
    DMAHandler.Init.PeriphDataAlignment = DMA_PDATAALIGN_WORD;  /*source transfers (flash) is peroformed in 32 bits values*/
    DMAHandler.Init.MemDataAlignment    = DMA_MDATAALIGN_WORD;  /*destination transfers (ram) will be performed in 32 bits values*/
    DMAHandler.Init.Mode        = DMA_NORMAL;                   /*Single transfer mode*/
    DMAHandler.Init.Priority    = DMA_PRIORITY_LOW;             /*transfer in low priority*/
    HAL_DMA_Init( &DMAHandler );

    /*Software trigger. start transfering info from DataSource array to Buffer*/
    HAL_DMA_Start( &DMAHandler, (uint32_t)&DataSource, (uint32_t)&Buffer, BUFFER_SIZE );
    
    /*just wait until the transfer is complete, one second is a lot*/
    HAL_Delay( 1000u );
    
    /*print the contents of variable Buffer*/
    printf( "-------Buffer Content-------------\r\n" );
    for( uint32_t i=0 ; i<BUFFER_SIZE/4u ;i++ )
    {
        printf( "0x%08lX, 0x%08lX, 0x%08lX, 0x%08lX\n\r", Buffer[(i*4)+0u], Buffer[(i*4)+1u], Buffer[(i*4)+2u], Buffer[(i*4)+3u] );
    }

    while(1)
    { 
    }
}