STM32F479 datasheet(31/91 Pages) STMICROELECTRONICS

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Creating a graphical application with LTDC

This section illustrates the different steps required before and during a graphical application

development using LTDC. The user should at first determine the graphical application

requirements, then check if the desired display size fits the hardware configuration. During

the graphical application compatibility check phase, the user can use the existing STM32

reference boards described in Table 17 to evaluate his hardware and software

configuration.

4.1

Determining graphical application requirements

Determining the graphical application needs is a crucial step to start from. Some of the most

important parameters to be defined before starting the creation of the graphical application

are: display resolution, color depth, as well as the nature of the data to display (static

images, text or animation).

Once the basic parameters mentioned above are defined, the user should determine the

graphical hardware architecture of the application as well as the required hardware

resources. The user should select the best-fitting STM32 package (see Table 13) according

to the following parameters:

•

If an external memory is needed for the framebuffer

•

The external framebuffer memory bus width

•

The LTDC interface: RGB565, RGB666 or RGB888 depending on the display module

•

If an external memory is needed to store graphic primitives (QSPI or FMC_NOR)

4.2

Checking the display size and color depth compatibility

with the hardware configuration

When starting a graphic application development using a STM32 microcontroller, the user

usually has a defined desired display size and color depth. A key question that the user

must answer before continuing the development is if such display size and color depth

match a specific hardware configuration?.

In order to answer this question, the user should follow below steps:

Determine the required framebuffer size and its location.

Check the compatibility of the display versus the framebuffer memory bandwidth

requirements.

Check the compatibility of the display panel interface with the LTDC.

4.2.1

Framebuffer memory size requirements and location

Determining the framebuffer memory size and its location is a key parameter for the display

compatibility check.

The memory space required in the RAM to support the framebuffer should be contiguous

and with a minimum size equal to:

Framebuffer size = number of pixels x bits per pixel

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