NanoPi NEO SPI Display PCD8544

viteo · June 15, 2023

I'm missing something essential.
I have NanoPi Neo v1.4 with Armbian 23.5 Jammy CLI (Linux nanopineo 6.1.30-sunxi). My display is Nokia5110 LCD or PCD8544

With spi-spidev DT I can successfully via `spidev0.0` with `spi-tools`. I.e. I confirm that spi is working.
Now, I studied about DTO and fbtft driver, found that it supports pcd8544.

I wrote this kind of DTO and added it to `armbianEnv.txt`

/*
* Device: LCD5110 (nokia5110) 1.6"(84x48px) SPI display Module PCD8544
* Module      Connector
* SDI(MOSI)	<-  PC0
* SCK		<-  PC2
* CS		<-  PC3
* RESET		<-  PA1
* DC/RS		<-  PA3
* LED		<-  PA2
*/

/dts-v1/;
/plugin/;

/ {
    compatible = "allwinner,sun8i-h3";
    
    fragment@0 {
        target = <&pio>;
        __overlay__ {
            display_pins: display_pins {
                pins = "PA1", "PA3"; /*RESET, DC_RS*/
                function = "gpio_out";
            };
        };
    };
    
    fragment@1 {
        target = <&spi0>;
        __overlay__ {
            /* needed to avoid dtc warning */
            #address-cells = <1>;
			#size-cells = <0>;
            status = "okay";
            cs-gpios = <&pio 2 3 0>; /* ChipSelect PC3 */
            pcd8544: pcd8544@0 {
                compatible = "philips,pcd8544";
                reg = <0>;
                pinctrl-names = "default";
                pinctrl-0 = <&display_pins>;
                spi-max-frequency = <4000000>;
                buswidth = <8>;
                fps = <5>;
                // led-gpios = <&pio 0 2 1>; /*LED=PA2*/
                reset-gpios = <&pio 0 1 1>; /*RESET=PA1*/
                dc-gpios = <&pio 0 3 0>; /*DC_RS=PA3*/
            };
        };
    };
};

I'm seeing in serial output `Applying user provided DT overlay sun8i-h3-spi-pdc8544.dtbo`

But...

Thats all.
`dmesg | grep spi` or `dmesg | grep fbtft` is empty.

`lsmod | grep fb` - also nothing.

`ls /dev/fb*` - nope.

If I manually call for `sudo modprobe spi:fb_pcd8544`
this prints into dmesg:

Quote

fbtft: module is from the staging directory, the quality is unknown, you have been warned.
fb_pcd8544: module is from the staging directory, the quality is unknown, you have been warned.
SPI driver fb_pcd8544 has no spi_device_id for philips,pcd8544

I've tried a lot of different tweaks in DTO, I've tried different releases from download page for my board.
I don't know what am I missing.
Is it somehow related to CLI nature of images?
Why does no fb device apeears?

Any help would be appreciated. Thank you.

Edited June 16, 2023 by viteo

Ryzer · June 15, 2023

Hi there,

does 'lsmod | grep pdc8544' even show that they module has even load? unfortunately the fbtft drivers are not that well supported hence being in the staging directory. I would advice that you look for a tiny drm based driver which is the way that small displays tend to be handled with the more recent kernel versions

best of luck

viteo · June 16, 2023

oh. i've looked at your reply and something catched my eye.

it's not `pdc8544` it's `pcd8544`

I was copypasting this alias string from internet for three days..
checked modinfo and there:

Quote

alias: spi:pcd8544
alias: spi:fb_pcd8544
alias: philips,pcd8544

i'm sorry. i'm so dumb.

Replaced with right string:

                compatible = "philips,pcd8544";

It's working now!

p.s. i've edited original post for the case someone copy DT code.

p.p.s. I'll take a loot at tinydrm, but googleing doen't give much for v6 kernel. if it's not a generic driver, there might not be pcd8544 tinydrm driver.

Edited June 16, 2023 by viteo

viteo · July 5, 2023

Guys, I'm lookig for your help again.

Trying to start this display with TinyDRM.
The module I looking for is `panel-mipi-dbi`. I've built Armbian with this module enabled.
Edited my dts as follows:

/dts-v1/;
/plugin/;

/ {
    compatible = "allwinner,sun8i-h3";
    
    fragment@0 {
        target = <&pio>;
        __overlay__ {
            display_pins: display_pins {
                pins = "PA1", "PA3", "PA2"; /*RESET, DC_RS*/
                function = "gpio_out", "gpio_out", "gpio_out";
            };
        };
    };
    
    fragment@1 {
        target = <&spi0>;
        __overlay__ {
            /* needed to avoid dtc warning */
            #address-cells = <1>;
            #size-cells = <0>;

            status = "okay";
            cs-gpios = <&pio 2 3 0>; /* ChipSelect PC3 */
            num-chipselects = <1>;

            panel: panel@0 {
                compatible = "pcd8544", "panel-mipi-dbi-spi";
                reg = <0>;
                spi-max-frequency = <4000000>;

                dc-gpios = <&pio 0 3 0>; /*DC_RS=PA3*/
                reset-gpios = <&pio 0 1 1>; /*RESET=PA1*/
                /*led-gpios = <&pio 0 2 0>; /*LED=PA2*/
                write-only;

                width-mm = <35>;
                height-mm = <27>;

                panel-timing {
                    hactive = <84>;
                    vactive = <48>;
                    hback-porch = <0>;
                    vback-porch = <0>;
                    clock-frequency = <0>;
                    hfront-porch = <0>;
                    hsync-len = <0>;
                    vfront-porch = <0>;
                    vsync-len = <0>;
                };
            };
        };
    };
};

Tried both variants with `<&pio>` target and without. Double checked aliases

Also added firmware `pcd8544.bin` to /lib/firmware

command 0x21 # Function set
command 0x04 # Temperature control (0)
command 0x17 # Bias system (4)
command 0x22 # Function set
command 0x0C # Display control

But no luck again. Module is not loaded, dmesg tells nothing =/
Also found this topic, but my display is still blank.

Edited July 5, 2023 by viteo

viteo · October 26, 2023

i've managed to create DRM driver for that display.
https://lore.kernel.org/linux-devicetree/20230807121022.1871-2-viteosen@gmail.com/
that was impressive jouney

pcd8544.c pcd8544-drm-spi.dts

robertoj · December 7

Hello viteo

Did you give up on the mipi-dbi-spi driver?

I have a st7796s, and I tried "compatible="4in,panel-mipi-dbi-spi" ", as suggested in https://forums.raspberrypi.com/viewtopic.php?t=358240&hilit=Ili9341#p2165638

and I saw your example as the only example of mipi-dbi-spi in armbian, so I am trying to modify your DTS

I tried "compatible=sitronix,st7796s" and it doesn't work

viteo · December 13

i'd made a new driver for PCD8544 display, because it is not compatible with mipi.
A lot of time has passed since then, but i found my dts for st7789. hope it help you.

st7789v-drm-spi.dts panel-mipi-dbi.dts

Edited December 13 by viteo