STM32F479 datasheet(46/91 Pages) STMICROELECTRONICS

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Creating a graphical application with LTDC

AN4861

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DocID029237 Rev 2

offset of the DMA2D equal to the difference between the closest burst multiple and

the actual line length data size.

–

The LTDC line length should always be equal to the active data size, but, the

LTDC pitch should be programmed with the value of the closest bytes number

multiple of 64 bytes.

The HAL_LTDC_SetPitch function provided under the hal_ltdc driver can be used to

program the desired pitch value in number of pixels. For the previous example, the

value of the pitch to pass to this function should be equal to 512 (512 is the number of

pixels per line corresponding to a line length size of 1536 bytes which is multiple of 64

bytes).

The code below is based on the HAL drivers and shows an example of setting the pitch

as described in Figure 27:

/* Setting the Layer1 window to 480x272 at positions X = 0 and Y = 0 */

pLayerCfg.WindowX0 = 0;

pLayerCfg.WindowX1 = 480;

pLayerCfg.WindowY0 = 0;

pLayerCfg.WindowY1 = 272;

pLayerCfg.PixelFormat = LTDC_PIXEL_FORMAT_RGB888;

pLayerCfg.Alpha = 255;

pLayerCfg.Alpha0 = 0;

pLayerCfg.BlendingFactor1 = LTDC_BLENDING_FACTOR1_PAxCA;

pLayerCfg.BlendingFactor2 = LTDC_BLENDING_FACTOR1_PAxCA;

/* Framebuffer start address: LTDC fetches the image directly from internal

Flash the real image width is 480 pixels but additional 32 pixels are added

to each line to get a 512 pixels pitch.

Only the 480 pixels width is displayed*/

pLayerCfg.FBStartAdress = (uint32_t)&image_data_Image_RGB888_512x272;

pLayerCfg.ImageWidth = 480;

pLayerCfg.ImageHeight = 272;

pLayerCfg.Backcolor.Blue = 0;

pLayerCfg.Backcolor.Green = 0;

pLayerCfg.Backcolor.Red = 0;

if (HAL_LTDC_ConfigLayer(&hltdc, &pLayerCfg, 0) != HAL_OK)

{

Error_Handler();

}

/* Sets the Layer1 (index 0 refers to Layer1) Pitch to 512 pixels */

HAL_LTDC_SetPitch(&hltdc, 512, 0);

Figure 27 describes the management of the memory after solving the previous

problem.

STM32F479 Datasheet(PDF) 46 Page - STMicroelectronics

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