STM32F479 datasheet(57/91 Pages) STMICROELECTRONICS

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Creating a graphical application with LTDC

4.7.3

LTDC layer(s) configuration

This section describes the needed steps to configure the LTDC layer(s) respecting the

display size and the color depth.

As previously stated in Section 3.3.2 the LTDC features two independently configurable

layers, where the user can enable either one or the two layers. By default both layers are

disabled so only the configured background color is displayed (the default color is black).

The user can display layer 1 + background or display layer 1 + layer 2 + background.

Display only the background

If no layer has been enabled, only the background is displayed. If the background color is

not configured, the default background black color is displayed

(LTDC_BCCR = 0x00000000).

To set a blue background color the LTDC_BCCR register should be set to 0x000000FF.

Layer parameters configuration

Once that the LTDC GPIOs, clocks and timings are properly set, the user should configure

the following LTDC layer parameters. Each LTDC layer has its own parameters so it should

be configured separately.

•

Window size and position

•

Pixel input format

•

Framebuffer start address

•

Framebuffer size (image width and image height) and pitch

•

Layer default color in ARGB8888 format

•

Layer constant alpha for blending

•

Layer blending factor1 and factor2

An example of LTDC layer parameters configuration using STM32CubeMX is described in

Section : LTDC Layer parameters configuration on page 75.

Note:

All layer parameters can be modified on the fly except for the CLUT. The new configuration

has to be either reloaded immediately or during vertical blanking period by configuring the

LTDC_SRCR register.

4.7.4

Display panel configuration

Some displays require to be configured using serial communication interfaces such as I2C

or SPI.

For instance the STM32F429I-DISCO is embedding the ILI9341 display module which is

initialized through the SPI interface.

A dedicated driver for this display module (ili9341.c) including initialization and configuration

commands is available in the STM32Cube firmware package under:

STM32Cube_FW_F4_Vx.xx.x\Drivers\BSP\Components\ili9341

An example of display initialization sequence based on the ili9341_Init() function is included

in the STM32Cube examples for the STM32F429I-Discovery board under

STM32Cube_FW_F4_Vx.xx.x\Projects\STM32F429I-Discovery\

Examples\LTDC\LTDC_Display_2Layers

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