STM32F479 datasheet(47/91 Pages) STMICROELECTRONICS

Nome de Peças	STM32F479

Descrição Electrónicos	LCD-TFT display controller (LTDC) on STM32 MCUs

PDF	91 Pages

Scroll/Zoom	100%

Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

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47 / 91 page

DocID029237 Rev 2

47/91

AN4861

Creating a graphical application with LTDC

Figure 27. Adding dummy bytes to make the line width multiple of 64 bytes

4.5.3

Optimizing the LTDC framebuffer fetching from SDRAM

Making random access into a bank generates some precharge cycles which increase the

SDRAM latency seen by the LTDC. As the LTDC is performing sequential accesses, it's

important that no other masters are doing access into the same SDRAM bank.

The external SDRAM is composed of multiple banks. Given that making random accesses

on a bank generates some precharge and activates some cycles, the framebuffer must be

placed in an independent bank accessed only by the LTDC. This action reduces the external

memory latency and leads to a higher throughput. As a consequence, when double

framebuffer technique is used, it is recommended to have these buffers in two separate

banks.

This can be done by storing the frontbuffer in the first address of the SDRAM and

addressing the backbuffer by adding an offset with the size of one bank. Refer to Figure 28.

STM32F479 Folha de dados(PDF) 47 Page - STMicroelectronics