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Connecting banana pi m2 zero with ili9341 display over spi on latest armbian image

yaya8888

By yaya8888
in Allwinner sunxi

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robertoj

robertoj

Posted
Posted

I tried all weekend to add the touch function of the LCD's XPT2046

 

With this DTS:

  Reveal hidden contents

It gets compiled, but the bootloader rejects it:

Applying user provided DT overlay ili9341-touch-sp0.dtbo

failed on fdt_overlay_apply(): FDT_ERR_NOT_FOUND

Error applying DT overlays, restoring original DT

(i included the spi-add-cs1.dtbo as suggested in https://ryjelsum.me/homelab/xpt2046-ili9341-opi-zero/ )

 

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Ryzer

Ryzer

Posted
Posted

Hi robertoj,

 

I can see some lines that look problematic. Firstly you are defining cs-gpio twice.

 

Once here:

  On 9/16/2024 at 7:27 AM, robertoj said: 
fragment@1 {
	target = <&spi0>;
	__overlay__ {
		pinctrl-names = "default", "default";
		pinctrl-1 = <&spi0_cs1>;
		cs-gpios = <0>, <&pio 2 7 0>; /* PC7 */
	};
Expand  

 Note - Remember that 0 refers to the native cs line (PC3)

 

  On 9/16/2024 at 7:27 AM, robertoj said: 
fragment@2 {
	target = <&spi0>;
	__overlay__ {
		/* needed to avoid dtc warning */
		#address-cells = <1>;
		#size-cells = <0>;
		status="okay";
		pinctrl-names = "default", "default"; /*added by ryjelsum*/
		cs-gpios = <&pio 2 3 0>, <&pio 2 7 0>; /* cs0=C3,cs1=C7 */
Expand  

 

Here the pinctrl references are wrong. I am not sure how strictly the ordering matters but for clarity 'pinctrl-names' should be before the actual pin control nodes.

  On 9/16/2024 at 7:27 AM, robertoj said: 
pinctrl-2=<&spi0_cs1 &spi0_cs1>;
			pinctrl-names = "default";
			pinctrl-3 = <&ads7846_pins>;
Expand  

 

Adding spi-add-cs1.dtbo is not needed as all it does it defined the pins to use as cs lines which you have already done above anyway. My other suggestion would be to look into what the latest bindings should for the ads7846 touch controller. Let me know how you get on with following overlay:

 

  Reveal hidden contents

 

best of luck

 

Ryzer

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robertoj

robertoj

Posted
Posted

I went with your corrected DTS ... so far it looks great

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(Did NOT use the spi-add-cs1.dtbo, as advised)

I went out running to work, and I will continue tests when I go back home

 

Day 2 of testing:

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evtest shows a random stream of events, then stops... then lcd touches dont get reactions.

 

I will check my wiring and order a new LCD, because mine has a cracked glass

 

Is there any way to tell that the SPI, IRQ, CS inputs/outputs to the XPT2046 (ADS 7846) is working correctly, and blame everything on a bad resistive panel?

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robertoj

robertoj

Posted
Posted

I had some success by changing the touch chip pins from:

CS1=PC7 PA18 (I avoided the "native Spi0 CS1 PC7" and used PA18)

IRQ=PA19 PA7 (maybe this was unnecessary)

 

New DTS:

  Reveal hidden contents

 

With inspiration from https://github.com/jonathan-gatard/ili9486-xpt2046/tree/main for the IOs and the analog parameters

 

Now sudo evtest prints an event each time I press on the LCD screen

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If an LCD suffers a disconnection and reconnection, is it possible to reset, re-initialize and continue working the LCD?

 

Or would it always need a Linux reboot?

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robertoj

robertoj

Posted
Posted

problem solved: IRQ i/o needed the reverse polarity in pendown-gpio. armbianEnv.txt and DTS here:

 

(it is working with sudo evtest, so I dont know if it needs calibration... and I wonder if I need to reverse the polarity in the interrupts line too)

 

  Reveal hidden contents

 

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robertoj

robertoj

Posted
Posted

I could run lightdm with

 

apt install xinit xterm xauth x11-apps xserver-xorg lightdm xserver-xorg-input-evdev xserver-xorg-video-fbdev

 

/usr/share/X11/xorg.conf.d/99-fbdev.conf:

Section "Device"

   Identifier "myfb"

    Driver "fbdev"

    Option "fbdev" "/dev/fb0"

EndSection

 

However, the cursor is moving at 90-degrees from my finger movement. Also, it is very unstable... it crashes, leaving a white screen. The white screen remains after reboot, and I can only make it work again by removing and connecting the 5V power.

 

Can someone share how they installed a window manager with ili9341?

 

is 24MHz too fast? Would native cs1 help anything?

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Ryzer

Ryzer

Posted
Posted (edited)

Hi robertoj,

 

There are addtional touchscreen parameters that you could try to address the cursor movement being wrong. based on what you have said I would suggest adding the line 'ti,swap-xy = <1>;' to: 

ads7846: ads7846@1 {
            reg = <1>; /* Chip Select 1 */
            compatible = "ti,ads7846";
            spi-max-frequency = <1000000>;
            status = "okay";
            pinctrl-names ="default";
            pinctrl-0 = <&ads7846_pins>;
            interrupt-parent = <&pio>;
            interrupts = <0 7 2>; /* PA7 IRQ_TYPE_EDGE_FALLING */
            pendown-gpio = <&pio 0 7 1>; /* PA7 */
            /* driver defaults, optional*/
            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 <0xFFFF>;
            ti,x-plate-ohms = /bits/ 16 <400>;
        };

 

In regards to the crashing that, will be a bit harder to pin down. Thinking about I would suggest double checking 'interrupts = <0 7 2>;' as I would have expected it to be something like 'interrupts = <0 7 IRQ_TYPE_EDGE_FALLING>. That said, it does appear to be registering correctly when looking here:

 

  On 9/16/2024 at 3:26 PM, robertoj said: 
gpio-19  (CON2-P27            |pendown             ) in  hi IRQ
Expand  

Does /proc/interrupts list the gpio as being set to trigger on falling edge as expected?

24MHz is the maximum speed that the ili9341 will work at in spi mode. It may be possible that there indeed problems with the driver but without investigating deeper its hard to say. Raspberry Pi have there own distinct linux kernel fork so the problems mentioned may not be common to the mainline kernel used by Armbian. I wonder if the crashes are possibly caused by the cs lines of both devices being pulled low at the same time under certain conditions.

 

best of luck

 

Ryzer

Edited by Ryzer
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robertoj

robertoj

Posted
Posted

Thank you. I will try that, and I learned about the xinput_calibrator, which I will apply next time.

(and https://github.com/reinderien/xcalibrate/blob/main/xcalibrate is a new interesting project)

 

Now I am focusing on moving the touchscreen pins to an independent gpio-based SPI set of pins... we will know whether the LCD crash is from interfering SPI commands.

 

I did an experiment with the "backlight = <&backlight_gpio>" parameter as shown in https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-LCD-ADAFRUIT-24-SPI0-00A0.dts

and https://forums.raspberrypi.com/viewtopic.php?t=358240  but so far it ended up in a kernel not loading. I will leave this task for last.

 

If the DTS configuration does not specify CPHA and CPOL, what is the default setting of the SPI protocol?

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robertoj

robertoj

Posted
Posted

I decided to use the gpio-spi driver, to emulate software spi just for the touch chip ADS7846/XPT2048, and use a different DTS file

 

Here is what I think would work: ads7846-spi-gpio.dts

  Reveal hidden contents

 

I used these references:

https://www.kernel.org/doc/Documentation/devicetree/bindings/spi/spi-gpio.txt
https://stackoverflow.com/questions/78905378/how-do-i-use-spi-gpio-driver-in-linux
https://gist.github.com/BjoernSch/39d3bca950a3b025b806decc2b686bbc

and need to check this too:

http://terminal28.blogspot.com/2015/12/bitbanging-spi-on-raspberry-pi-via-spi.html

http://terminal28.blogspot.com/2016/05/enabling-spi1-on-raspberry-pi-bzero23.html

 

My DTS compiles well :) but the linux in my armbian image did not include spi-gpio.ko, in /lib/modules/6.6.44-current-sunxi/kernel/drivers/spi/

 

Therefore, I am building a new OS image.

 

Does anyone see a problem with my DTS?

 

 

Update:) it works :) good stability 

 

now the only problem is that both x-axis and y-axis are reversed (not swapped). More updates on the way

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Ryzer

Ryzer

Posted
Posted

Hi robertoj,

 

  On 9/26/2024 at 4:03 PM, robertoj said:

If the DTS configuration does not specify CPHA and CPOL, what is the default setting of the SPI protocol?

Expand  

This would most like be set somewhere within the SPI controller driver.

 

I tried that in my other post with not much success but I will try to give it another shot.

 

maybe you could try reversing the min and max values

 

best of luck

 

Ryzer

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robertoj

robertoj

Posted
Posted

I simply rotated the image with the "rotation" parameter in the LCD DTS, and turned the screen 180 degrees physically. :D 

 

I will try the min, max swap later, but right now I am on a roll, making my tkinter apps work :)

Another thing I will try is not using a chip select pin at all, since LCD and touch-chip are on different buses now.

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Koliber93

Koliber93

Posted
Posted (edited)

Hi all, I tried to compile codes from this topic on my banana pi m2 berry but it still don't work, I tried with chat gpt implement my pins but in my analyzer I cannot see anything on ouptut, on dmesg of spi I have information about timeout of connecting to ili9341. Below I put my dts configuration: 
 

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Below I put information from dmesg :
 

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Have you any idea to prepare good configuration ? 

Edited by Koliber93
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robertoj

robertoj

Posted
Posted

Change:

reset-gpios = <&pio 7 27 1>; /* GPIO 24 */

to:

reset-gpios = <&pio 7 27 0>; /* GPIO 24 */

 

Change the SPI speed to 24MHz

 

Format your DTS so we can read it easily.

Correct the comments with GPIO nnn because they are confusing. 

Show a wiring schematic between the BPI M2 Berry and your LCD

Use the "Spoiler" (eye) button, so that your long texts don't take so much space.

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Koliber93

Koliber93

Posted
Posted

Thank you for quick reply, my current configuration is :
MOSI - GPIO10 (PIN19)
MISO - GPIO9 (PIN21)
SCLK - GPIO 11 (PIN23)
CS - GPIO8 (PIN24)
DC - GPIO24 (PIN18)
RESET - GPIO25 (PIN22)
Below I put the picture with 40-pin header description.

  Reveal hidden contents

I also found the issue with spi0 on Banana PI M2 Berry and I also try this configuration - for this issue I found another configuration and I tried mixed it together : 
 

  Reveal hidden contents

The only difference what I noticed is that I had some signals on the output as you can see below from my pulseview:
 

  Reveal hidden contents

Another issue what I concern is problem with DMA from dmesg

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robertoj

robertoj

Posted
Posted

Try all combinations of (I have no idea why these things sometimes work):

 

* Only define the PH26,PH27 in pins = "PC0", "PC1", "PC2", "PC23", "PH26", "PH27";

* only cs-gpios = <0>; //use default CS instead of cs-gpios = <&pio 2 23 0>; /* PC23 for CS */

 

Make sure that there are no erorrs in:

dmesg|grep spi

dmesg|grep mipi

 

Usually these are good signs:

lsmod|grep ili shows a loaded kernel module

ls /dev/fb* shows a created video device

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Ryzer

Ryzer

Posted
Posted

Hi Koliber93,

 

Before trying to the ili9341 display working can you confirm that spi0 works with a simple spidev setup then move onto to trying to configure the display. Do not mix up pin functions, you should have a seperate node for the spi pins and additional gpio used for the display. Normaly the spi pins should already defined under the pinctrl node in which case we can simply refer to associated label. for reference please see: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm/boot/dts/allwinner/sun8i-r40.dtsi?h=v6.6.66 As suggested by robertoj, I would stick with the hardware cs pin as I have had nothing but problems with gpio defind cs lines in recent kernels. If a simple SPI set works then please feel free to try the following overlay: 

/dts-v1/;
/plugin/;

/ {
        compatible = "allwinner,sun8i-h3", "allwinner,sun8i-r40";

        fragment@0 {
                target = <&pio>;

                __overlay__ {
                        display_pins: display_pins {
                                pins ="PH26", "PH27";
                                function ="gpio_out", "gpio_out";
                        };
                };
        };

        fragment@1 {
                target = <&spi0>;

                __overlay__ {
                        #address-cells = <1>;
                        #size-cells = <0>;
                        status = "okay";
			pinctrl-names = "default", "default";
                        pinctrl-0 = <&spi0_pc_pins>;
			pinctrl-1 = <&spi0_cs0_pc_pin>;
                        cs-gpios = <0>; /* PC23 for CS */
                        num-chipselects = <1>;

                        display: display@0 {
                                compatible = "adafruit,yx240qv29", "ilitek,ili9341";
                                reg = <0>;
                                pinctrl-names = "default";
                                pinctrl-0 = <&display_pins>;
                                spi-max-frequency = <24000000>;
                                rotation = <270>;
                                bgr = <0>;
                                fps = <10>;
                                buswidth = <8>;
                                height = <240>;
                                width = <320>;
                                reset-gpios = <&pio 7 26 0>; /* PH26 for Reset */
                                dc-gpios = <&pio 7 27 0>;    /* PH27 for Data/Command */
                                debug = <3>;
                        };
                };
        };

        __overrides__ {
                rotation = <&display>, "rotation:0";
                fps = <&display>, "fps:0";
                debug = <&display>, "debug:0";
        };
};

I do find it strange however that you are not getting any activity on the DC line, are you sure you have probes labelled correctly?

 

Best of luck

Ryzer

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