1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Configuration of LCD with Linux

Discussion in 'ARM' started by LucasM, Feb 22, 2018.

  1. LucasM

    LucasM New Member

    Feb 22, 2018
    Hello, I am trying to launch thePH320480T009-LAC03 tft with an IMX7 that uses an Yocto image. The driver that uses the tft is ST7769S, however the kernel of yocto does not provide this driver, therefore I am using the ili9486 that has a very similar operation. To configure this driver I have made the following configuration of the device tree to put the SPI 4-Line interface(First I have removed the previous configuration of mxcfb1 from the device tree):


    status = "okay";

    spidev@1 {

    compatible = "rohm,dh2228fv";

    spi-max-frequency = <60000000>;

    reg = <1>;

    status = "disabled";


    mxcfb1: fb@0 {

    compatible = "ilitek,ili9486";

    reg = <0>;

    spi-max-frequency = <5000000>;

    rotate = <0>;

    buswidth = <8>;

    regwidth = <16>;

    reset-gpios = <&gpio 25 0>;

    dc-gpios = <&gpio 24 0>;

    debug = <0>;

    init = <0x20000ff





    0x10000f0 0xc3

    0x10000f0 0x96

    0x1000036 0x40

    0x10000b4 0x01

    0x10000b6 0x20 0x02 0x3b

    0x10000e8 0x40 0x8a 0x00 0x00 0x29 0x19 0xa5 0x33

    0x10000c1 0x0x06

    0x10000c2 0xa7

    0x10000c5 0x18

    0x10000e0 0x0f 0x09 0x0b 0x06 0x04 0x15 0x2f 0x54 0x42 0x3c 0x17 0x14 0x18 0x1b

    0x10000e1 0x0f 0x09 0x0b 0x06 0x04 0x03 0x2d 0x43 0x42 0x3b 0x16 0x14 0x17 0x1b

    0x10000f0 0xc3

    0x10000f0 0x96





    The initial sequence is the recommended by the manufacturer of the tft. When I start the program, I see that the screen responds to the commands I am indicating in the initial sequence, since when the last command of that sequence is displayed (display on), the display turns on and shows many colored dots. And this is all that the screen does, when I indicate that I upload an image (I launch a program generated with the qt creator), it does not work, it still shows the colored dots. I have measured the signal that comes out of the SPI with an oscilloscope, and the signals it generates seem correct.

    What could be the problem?

    My theory is that the "b6h" command that is launched in the initial sequence activates a bit (RM) that is to select the RGB interface, therefore when I load an image by the SPI interface the screen ignores it, since the wait that the signal arrives for another data bus.

    How would I have to configure the initial sequence to load the image by the SPI?

    How would I have to configure the device tree so that it would also generate an RGB interface?


Share This Page