Using 16-bit Interface to a NHD-2.4-240320AF-CTXP-T Display

Bob Juncosa

Hi.  I am using a NHD-2.4-240320AF-CTXP-T display that is being controlled by an ESP32-S3.  Although this application is not speed critical, since I have the GPIO available, I would like to take advantage of the 8-bit or 16-bit parallel interface.  I have looked over your sample code and have not been able to find an example with a library that I can use as the basis for my application.  Eventually, this will be a gauge type of application so I will need to have the ability to manipulate image bits stored on an SD or memory.

Your help is creatly appreciated.

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4 comments

Date Votes
  • Engineering Support
    Community moderator

    Hi Bob,

    Thanks for your post.  While we have not tested this personally, it should be possible to implement this using the TFT_eSPI library on Github.  You will need to modify the User_Setup.h file to specify the ST7789 driver and the 16-bit parallel interface.  Please let us know if you are able to successfully implement this library.

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  • Bob Juncosa

    It is supposedly possible with that library but there are severe limitations.  The biggest is that ALL of the data lines must be on GPIO pins 0-31.  This is because it uses just one register for processing data.  Otherwise, two register writes are necessary.  Because of all the other functions in my application, I was not able to put all of the lines in that bank.  I was hoping that since you had designed the display to support 16-bits, you had libraries or other code to be used as a starting point for parallel data.

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  • Bob Juncosa

    I am still have a heck of a time.  As you know with displays, nothing works until everything works.  I have decided to start with the simplest configuration and that would be using the SPI interface.  I am using the Adafruit GFX and ST7789 libraries.  I am not sure I have the pin assignmens correct.  Here is what I have connected to your display...

    MOSI >> SDA (Serial Input)
    CSX to CSX (Chip Select)
    SCLK to DCX (Serial Clock)
    RESX to RESX (Reset)
    IM0 to HIGH
    IM2 to HIGH

    It is the DCX connection that I am not sure about.  The library calls for identifying a Data/Command connection and a clock connection.  The data sheet for the display shows that the serial clock should be connected to the DCX pin.  Do I have that correct?

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  • Engineering Support
    Community moderator

    Hi Bob,

    I believe the issue you are experiencing is due to the fact that the NHD-2.4-240320AF-CTXP-T display only supports 3-wire SPI interface, and the graphics library appears to be designed for 4-wire SPI.  I was able to successfully get the library working with our NHD-2.4-240320CF-BSXV-FT display, which supports 4-wire SPI.  If you are able to, please try your setup with a display that supports 4-wire SPI.

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