EXTDMA
EXTDMA is in HCPU, used for efficient data transfer between memory-to-memory (especially data transfer related to PSRAM, more efficient than DMA memory-to-memory transfer), and can perform real-time lossy compression of images during transfer (52x does not support).
Main Features
Both source and destination addresses use 4-byte access, and addresses must be 4-byte aligned, length must also be 4-byte aligned
Source and destination addresses independently support BURST access (BURST1/4/8/16), and support automatic address increment
Single configuration maximum transfer unit count is 2^20-1, each unit is 4-byte transfer, i.e., single maximum transfer 4M bytes
Supports 3 event flags - transfer complete, half transfer, transfer error
Can be configured as image compression mode, supports RGB565/RGB888/ARGB8888 format input
Compression Ratios for Various Color Formats (10 levels)
rgb565 {1.33, 1.47, 1.6, 1.73, 1.87, 1.93, 2, 2.13, 2.26, 2.4}
rgb888 {2, 2.2, 2.4, 2.6, 2.8, 2.9, 3, 3.2, 3.4, 3.6}
argb8888 {2.67, 2.93, 3.2, 3.47, 3.73, 3.86, 4.0, 4.27, 4.53, 4.8}
EXTDMA Example 1
Compress and transfer 100x100 size RGB888 image at address 0x20000000 to 0x60000000, compression level 1 (i.e., 2x)
static volatile HAL_StatusTypeDef endflag;
static EXT_DMA_HandleTypeDef DMA_Handle = {0};
void EXTDMA_IRQHandler(void)
{
/* enter interrupt */
rt_interrupt_enter();
HAL_EXT_DMA_IRQHandler(&DMA_Handle);
/* leave interrupt */
rt_interrupt_leave();
}
static void dma_done_cb()
{
endflag = HAL_OK;
}
static void dma_err_cb()
{
endflag = HAL_ERROR;
}
void main(void)
{
HAL_StatusTypeDef res = HAL_OK;
uint32_t len;
/*Data copy config */
DMA_Handle.Init.SrcInc = HAL_EXT_DMA_SRC_INC | HAL_EXT_DMA_SRC_BURST16; //Source address auto-increment and burst 16
DMA_Handle.Init.DstInc = HAL_EXT_DMA_DST_INC | HAL_EXT_DMA_DST_BURST16; //Dest address auto-increment and burst 16
/*Compression config */
DMA_Handle.Init.cmpr_en = true;
if(DMA_Handle.Init.cmpr_en)
{
DMA_Handle.Init.src_format = EXTDMA_CMPRCR_SRCFMT_RGB888;
DMA_Handle.Init.cmpr_rate = 1;
DMA_Handle.Init.col_num = 100;
DMA_Handle.Init.row_num = 100;
}
len = DMA_Handle.Init.col_num * DMA_Handle.Init.row_num * get_byte_per_pixel(DMA_Handle.Init.src_format) / 4;
res = HAL_EXT_DMA_Init(&DMA_Handle);
HAL_EXT_DMA_RegisterCallback(&DMA_Handle, HAL_EXT_DMA_XFER_CPLT_CB_ID, dma_done_cb);
HAL_EXT_DMA_RegisterCallback(&DMA_Handle, HAL_EXT_DMA_XFER_ERROR_CB_ID, dma_err_cb);
/* NVIC configuration for EXTDMA transfer complete interrupt */
HAL_NVIC_SetPriority(EXTDMA_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(EXTDMA_IRQn);
HAL_EXT_DMA_Start_IT(&DMA_Handle, 0x20000000, 0x60000000, len);
}