5.1. DMA - Data Transfer Between RAM

This demo is based on the memory to memory mode of DMA for data transfer.

5.1.1. Hardware Connection

None

5.1.2. Software Implementation

  • For the code see examples/dma/dma_m2m

 1#define BSP_USING_DMA0_CH0
 2
 3#if defined(BSP_USING_DMA0_CH0)
 4#ifndef DMA0_CH0_CONFIG
 5#define DMA0_CH0_CONFIG \
 6{   \
 7.id = 0, \
 8.ch = 0,\
 9.direction = DMA_MEMORY_TO_MEMORY,\
10.transfer_mode = DMA_LLI_ONCE_MODE, \
11.src_req = DMA_REQUEST_NONE, \
12.dst_req = DMA_REQUEST_NONE, \
13.src_width = DMA_TRANSFER_WIDTH_32BIT , \
14.dst_width = DMA_TRANSFER_WIDTH_32BIT , \
15}
16#endif
17#endif

  • Enable BSP_USING_DMA0_CH0 and configure the DMA device, see bsp/board/bl706_iot/peripheral_config.h

 1dma_register(DMA0_CH0_INDEX, "DMA", DEVICE_OFLAG_RDWR);
 2
 3struct device *dma = device_find("DMA");
 4
 5if (dma)
 6{
 7    device_open(dma, 0);
 8    device_set_callback(dma, dma_transfer_done);
 9    device_control(dma, DEVICE_CTRL_SET_INT, NULL);
10}

  • First call the dma_register function to register a channel of the DMA device, currently register DMA_CH0

  • Then use the find function to find the handle corresponding to the device and save it in the dma handle

  • Finally use device_open to open the dma device in the default mode, call device_set_callback to register a dma channel 0 interrupt callback function, and call device_control to open the dma transmission completion interrupt

1dma_reload(dma,(uint32_t)dma_src_buffer,(uint32_t)dma_dst_buffer,8000);
2dma_channel_start(dma);

  • Call the dma_reload function to supplement the configuration of dma channel 0. A part of the configuration has been supplemented in DMA0_CH0_CONFIG. Here we mainly supplement the source data address, destination data address and total transmission length

  • Call dma_channel_start to start dma transmission

 1void dma_transfer_done(struct device *dev, void *args, uint32_t size, uint32_t state)
 2{
 3    uint32_t index=0;
 4
 5    if(!state)
 6    {
 7        MSG("dma transfer task done\r\n");
 8
 9        for(index=0;index<8000;index++){
10            if(dma_dst_buffer[index]!=0xff){
11                MSG("dma transfer error\r\n");
12            }
13        }
14
15        MSG("dma transfer success\r\n");
16    }
17
18}

  • Check whether the data transmission is correct in the interrupt function

5.1.3. Compile and Program

1 $ cd <sdk_path>/bl_mcu_sdk
2 $ make BOARD=bl706_iot APP=dma_m2m

5.1.4. Experimental Phenomena

The data in the dma_src_buffer array is transferred to the dma_dst_buffer array through DMA channel 0 with a source 32-bit width and a target 32-bit width. After the data transfer is completed, the serial port prints dma transfer success.