KeDei LCD / TFT module version 6.3 SPI blues

Discussion in 'Homebrew and Kit Projects' started by AA7EJ, Jan 17, 2019.

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  1. AA7EJ

    AA7EJ Ham Member QRZ Page

    Sorry for the rant.
    I am still struggling with coding LCD for my VNA.
    The latest by KeDei seems to have odd SPI hardware.
    The SPI MOSI signal is passed thru cascaded shift registers , consequently the "standard" ILI9341 LCD controller
    commands / data instead of single character are wrapped into 4 character array.
    Of course there is no visible documentation explaining this scheme, only some ancient C code.
    This funky scheme must be how KeDei switches the ILI9341 controller chip from command to data.
    73 Shirley

    PS Unless you have an idea or interested about how this shift register scheme works, no reply necessary.
     
  2. K3KIC

    K3KIC Ham Member QRZ Page

    I'm learning that before I buy these types of devices I want to be sure there is other information out there from those who used the part.
    I too am getting frustrated with poorly documented assemblies. Sometimes it's easier to simply buy another that is better supported and stop banging your head against the wall.
     
  3. AA5CT

    AA5CT Ham Member QRZ Page

    Just a question, do you have access to a logic analyzer? Even a simple one like some of the HP scopes had built-in once upon a time were useful for looking at bits going back and forth, kinda reassures one that the software is working as one expects, kicking out the bits in the right 'endiness' (big endian, little endian), catches maybe random glitches that occur and so forth.

    Full disclosure: I used an HP 1615A extensively once upon a time, its not a very complex beast, but it got the job done.
     
  4. AA7EJ

    AA7EJ Ham Member QRZ Page

    No, I do not.
    And my trusty old Tek 464 is still dissembled .
    Perhaps I need to fix hardware first.
    As far as this display goes - the SPI interface does not mean didly.
    It is same old story - how to switch from command to data.
    But I am making some progress.
     
  5. AA7EJ

    AA7EJ Ham Member QRZ Page

    Update
    After exhaustive search and with Mrs Google help I have concluded that this device IS NOT wired for full SPI interface , particularly MISO for LCD.
    Could blame it on e-bay , but.....

    Only TFT controller is wired for MISO - duh!

    73 from totally exhausted Shirley

    CASE CLOSED
     
  6. KEON

    KEON QRZ Member

    It is recommended that you use the STONE TFT LCD module
     

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