STM32F4 DMA2D

图像处理的专门DMA

看一段示例代码

 1 /**
 2   * @brief  Displays a line.
 3   * @param Xpos: specifies the X position.
 4   * @param Ypos: specifies the Y position.
 5   * @param Length: line length.
 6   * @param Direction: line direction.
 7   *   This parameter can be one of the following values: Vertical or Horizontal.
 8   * @retval None
 9   */
10 void LCD_DrawLine(uint16_t Xpos, uint16_t Ypos, uint16_t Length, uint8_t Direction)
11 {
12   DMA2D_InitTypeDef      DMA2D_InitStruct;
13
14   uint32_t  Xaddress = 0;
15   uint16_t Red_Value = 0, Green_Value = 0, Blue_Value = 0;
16
17   Xaddress = CurrentFrameBuffer + 2*(LCD_PIXEL_WIDTH*Ypos + Xpos);
18
19   Red_Value = (0xF800 & CurrentTextColor) >> 11;
20   Blue_Value = 0x001F & CurrentTextColor;
21   Green_Value = (0x07E0 & CurrentTextColor) >> 5;
22
23   /* Configure DMA2D */
24   DMA2D_DeInit();
25   DMA2D_InitStruct.DMA2D_Mode = DMA2D_R2M;
26   DMA2D_InitStruct.DMA2D_CMode = DMA2D_RGB565;
27   DMA2D_InitStruct.DMA2D_OutputGreen = Green_Value;
28   DMA2D_InitStruct.DMA2D_OutputBlue = Blue_Value;
29   DMA2D_InitStruct.DMA2D_OutputRed = Red_Value;
30   DMA2D_InitStruct.DMA2D_OutputAlpha = 0x0F;
31   DMA2D_InitStruct.DMA2D_OutputMemoryAdd = Xaddress;
32
33   if(Direction == LCD_DIR_HORIZONTAL)
34   {
35     DMA2D_InitStruct.DMA2D_OutputOffset = 0;
36     DMA2D_InitStruct.DMA2D_NumberOfLine = 1;
37     DMA2D_InitStruct.DMA2D_PixelPerLine = Length;
38   }
39   else
40   {
41     DMA2D_InitStruct.DMA2D_OutputOffset = LCD_PIXEL_WIDTH - 1;
42     DMA2D_InitStruct.DMA2D_NumberOfLine = Length;
43     DMA2D_InitStruct.DMA2D_PixelPerLine = 1;
44   }
45
46   DMA2D_Init(&DMA2D_InitStruct);
47   /* Start Transfer */
48   DMA2D_StartTransfer();
49   /* Wait for CTC Flag activation */
50   while(DMA2D_GetFlagStatus(DMA2D_FLAG_TC) == RESET)
51   {
52   }
53
54 }

LCD_DrawLine

里面不好理解的是offset那块，其他统一模式设置看看手册即可，这个offset设置我们先看寄存器是哪个

/* Configure the line Offset */
DMA2D->OOR &= ~(uint32_t)DMA2D_OOR_LO;
DMA2D->OOR |= (DMA2D_InitStruct->DMA2D_OutputOffset);

寄存器定义：

再看代码那几句：

if(Direction == LCD_DIR_HORIZONTAL)
{
DMA2D_InitStruct.DMA2D_OutputOffset = 0;
DMA2D_InitStruct.DMA2D_NumberOfLine = 1;
DMA2D_InitStruct.DMA2D_PixelPerLine = Length;
}
else
{
DMA2D_InitStruct.DMA2D_OutputOffset = LCD_PIXEL_WIDTH - 1;
DMA2D_InitStruct.DMA2D_NumberOfLine = Length;
DMA2D_InitStruct.DMA2D_PixelPerLine = 1;
}

if里很明白，在指定位置没有offset画一条length长的线

else是画的竖线，所以每行只画一个点，画length条线，所以每行只画一个点，offset的值就是：LCD_PIXEL_WIDTH - 1