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selamu
Explorer
June 22, 2025
Solved

Interfacing STM32F429VIT6 with TFT LCD display without using external RAM

  • June 22, 2025
  • 2 replies
  • 931 views

Hi ST community,

 

Recently i am working on a project, home automation, and i would like to use STM32F429VIT6 MCU and 3.5 inch 320RGB x 480 LCD display on the project. The LCD display controller is ST7365P from Sitronix, with Frame Memory Size: 320 x 480 x 18-bit = 2,764,800 bits. 

My question is, is it possible to interface STM32F429VIT6 MCU with the TFT-LCD display through LTDC without using an external RAM just by using the On-chip Frame Memory?

 

Attached are the TFT-LCD display and the ST7365 controller datasheet.

 

Regards,

    This topic has been closed for replies.
    Best answer by MM..1

    TouchGFX 4.25 introduces emulated framebuffer (patent pending), which takes significantly less space in memory by breaking the image to be displayed into chunks and using a memory mapping technique that does away with the graphical RAM on the display itself. Consequently, systems that previously required external RAM can now run on a single-chip board, thus lowering the bill of materials. Moreover, because ST integrated the technology at the middleware level, developers can take advantage of it by choosing the right option in TouchGFX Generator to see if it makes sense for their project. It also forces engineers to look more closely at their framebuffer strategy to see if it fits their application, something that too many often overlook.

    Or try normal partial mode SPI set area ... RGB send data...

    2 replies

    A
    AScha.3
    Super User
    June 22, 2025

    Hi,

    >TFT-LCD display through LTDC without using an external RAM

    Yes, these kind of displays have the frame buffer RAM on the driver chip, so need no other ram for running.

    I use similar TFTs , with ILI9343 or ST7789 etc, but always using the SPI interface (less wiring and needed pins).

    Writing to the picture is little slower, but as long as you dont want show a video or a fast game, but more a "info sceen" , no need for super fast picture update.

     

    AScha3_0-1750575178400.png

    I just looked on github for a driver, ST7365 seems unusual, i found nothing...

    S
    selamuAuthor
    Explorer
    June 22, 2025

    Hi,

     

    Thank you for your reply.

    Yes, SPI interface uses less wiring. The TFT-LCD display I have, LCM interface is SPI+RGB. This means the SPI interface can be used to send pixel data to the display rather than initializations?

     

    Regards,

    A
    AScha.3
    Super User
    June 22, 2025

    Right, see my pic...its just on a bluePill , F103 , 7 wires to display.

    E
    ethanmusk89
    Visitor II
    June 22, 2025

    No, the STM32F429VIT6 doesn’t have enough internal RAM to drive a 320x480 LCD via LTDC without external memory — it only has 256KB SRAM, while the display needs over 2.6MB.

    I ran into a similar issue and noted a few possible workarounds here: executordeltacom  — in case it helps.

    S
    selamuAuthor
    Explorer
    June 25, 2025

    The display has 345.6Kb (320 x 480 x 18-bit = 2,764,800 bits) internal GRAM. So this internal RAM can't be used instead of external RAM? 

    A
    AScha.3
    Super User
    June 25, 2025

    These kind of TFTs have the needed RAM on-chip of controller, so no RAM on cpu is needed.

    Just all picture content is written to the TFT controller; some libs are made for this, so all you need is to look for such a lib . Maybe touchGFX can do it also (i am not sure).

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