ST7796 display w/ opiz3

Eric Johnson · December 19

I know I need to find out which drivers to use... I just don't know where to start, I know I've seen some people having success with these displays - ili9488, and a couple others - I just don't know if this fits one of those overlays or not. (nothing I've tried so far has worked).

Any help identifying and pointing in the right direction, I would greatly appreciate. Trying to get this to work on my Orange Pi Zero 3 4gb.

(uploading images has failed.... so I guess I'll link them?)

https://imgur.com/a/NORYCj7

*edit 12/21 - renamed topic since I've Identified the display, going to track my (our?) progress with trying to get it to work.

Edited December 21 by Eric Johnson
identified first issue

Eric Johnson · December 20

I got a reply from the manufacturer. ST7796.

Will this DTS work with the ST7796? (going to try it this weekend if no other solution mentioned beforehand)

Edited December 20 by Eric Johnson

WDR_s · December 22

Hello
Try this one, it might work on your screen.

Eric Johnson · December 22

Quote

Hello
Try this one, it might work on your screen.

That uses a different touch controller than my screen (FT6236 vs my XPT2046).

robertoj · Thursday at 11:41 AM

Check here for the byte command sequence for st7796s and combine with the dts in my thread

https://forums.raspberrypi.com/viewtopic.php?t=380704

using the dts as is with your different touch controller likely wont hurt it, it may just throw error messages in dmesg|grep spi

or delete the touch part of the dts, or disconnect the spi pins to the touch controller if you want to be safer.

Eric Johnson · Thursday at 06:20 PM

Quote

Check here for the byte command sequence for st7796s and combine with the dts in my thread

https://forums.raspberrypi.com/viewtopic.php?t=380704

using the dts as is with your different touch controller likely wont hurt it, it may just throw error messages in dmesg|grep spi

or delete the touch part of the dts, or disconnect the spi pins to the touch controller if you want to be safer.

to be clear, do you mean the 9341 dts (which uses the xpt2046 touch control, which my display has) or the 9488 dts?

I haven't gotten as far as trying anything yet, I'm having trouble getting the SPI to work on my opiz3. Either that, or I'm having trouble getting wiringOP to work properly enough on Armbian in order to verify SPI is working. wiringOP verifies other GPIO as functional (and so does my meter) - but SPI seems to be a no-go. I've tried every SPI overlay in the armbian-config utility.

robertoj · Friday at 05:06 AM

I meant the ili9488 DTS

Also avoid using any other SPI related DTS, when working with a LCD DTS. They will interfere with each other.

Use only the ili9488 DTS that I posted, only changing:

* the GPIO number codes, to make it fit your wiring connections

* the content of the *.txt file with the one in the raspberry forum

Eric Johnson · 2024-12-28T20:35:03Z

Ok. My efforts have been futile... but then again, I'm a noob at this. I'm thinking my pin numbers aren't matching up properly - I'm not 100% that I understand the <&pio 1 2 3> format. I have no clue what the first number is, I'm guessing the second number is the pin, and the third is high/low? (forgive my ignorance, I've tried researching this, but am not finding anything specific to this)

the changes marked in that raspberry pi forum I made to armbianEnv.txt (I'm assuming that's the armbian equivalent to the pi's config.txt?) - but it just occurred to me that the format is different. I don't think the armbian file uses "dtoverlay", rather just "overlay". I'll adjust that now and see if that makes a difference. (edit - no matter what I do there, it doesn't load. absolutely nothing in dmesg about it one way or another)

This is what I've got:

/dts-v1/;
/plugin/;
/ {
    compatible = "allwinner,sun50i-h616";
    fragment@0 {
        target = <&spi1>;
        __overlay__ {
            status = "okay";
            cs-gpios = <&pio 7 24 0>,<&pio 2 26 0>; //chip select  pins 24 for LCD, 26 for touch
            panel: panel@0 {
                compatible = "panel-mipi-dbi-spi";
                reg = <0>;
                spi-max-frequency = <40000000>;
                width-mm=<79>;
                height-mm=<52>;
                reset-gpios = <&pio 2 22 0>; // pin 22, PC7
                dc-gpios = <&pio 2 18 0>; // pin 18, PC14
                write-only;
                format = "b6x2g6x2r6x2";
                panel-timing {
                    hactive = <480>;
                    vactive = <320>;
                    hback-porch = <0>;
                    vback-porch = <0>;
                    clock-frequency = <0>;
                    hfront-porch = <0>;
                    hsync-len = <0>;
                    vfront-porch = <0>;
                    vsync-len = <0>;
                };
            };

            ads7846: ads7846@1 {
                compatible = "ti,ads7846";
                reg = <1>;
                pinctrl-names = "default";
                spi-max-frequency = <1000000>;
                interrupt-parent = <&pio>;
                interrupts = <2 11 2>; /* PC6, pin 11 */
                pendown-gpio = <&pio 2 11 1>; /* PC6, pin 11  */

                /* OPTIONS */
                ti,x-min = /bits/ 16 <0>;
                ti,y-min = /bits/ 16 <0>;
                ti,x-max = /bits/ 16 <0xFFF>;
                ti,y-max = /bits/ 16 <0xFFF>;
                ti,pressure-min = /bits/ 16 <0>;
                ti,pressure-max = /bits/ 16 <0xFFF>;
                ti,x-plate-ohms = /bits/ 16 <400>;
                ti,swap-xy = <1>;
            };
        };
    };
};

Edited 17 hours ago by Eric Johnson