ROC-RK3328-CC 3.5 inch SPI LCD Touch Screen Display

I did a quick test and can confirm it’s not quite working yet. I used a 2GB ROC-RK3328-CC with fully-patched Libre image of Ubuntu 22.04 and a generic 3.5" RPi SPI touchscreen display that I had working on Le Potato. I’ll list some of what I saw at the end, but if you want to try it anyway I did a combination of steps from https://hub.libre.computer/t/aml-s905x-cc-480x320-ili9486-spi-touchscreen-display/183 and https://hub.libre.computer/t/libre-computer-wiring-tool/40

sudo ltdo list did not show the overlays, as expected – they haven’t been fully released yet. So had to pull the current github development code and try it.
cd # back to home directory
mkdir touchscreen # create a directory to work in
cd touchscreen # enter the new directory
sudo apt install git # install/update the git tools if not already installed
git clone https://github.com/libre-computer-project/libretech-wiring-tool.git # clone the repository
cd libretech-wiring-tool # enter the code directory
sudo ./install.sh # run the Libre-provided build script
sudo ./ldto list # run the newly-created version in the current directory and note additional overlays
sudo ./ldto enable spi0-cs1 # enable the SPI overlay using the new ldto for testing
sudo ./ldto enable spi0-cs1-ili9486-xpt2046 # enable the display and touch overlay using the new ldto
dmesg | grep fb # check if new fb was enumerated
ls /dev/fb* # see if new fb device was created

At this point the display showed some signs of life and could be seen in Display Properties in the windowing environment, so I did the merge to make it available on next boot.

sudo ./ldto merge spi0-cs1 # merge the SPI overlay using the new ldto
sudo ./ldto merge spi0-cs1-ili9486-xpt2046 # merge the display and touch overlay using the new ldto

On the first reboot, I think I hit the race condition – the boot messages scrolled by and showed fb0 (my main screen) enumerated, and then it hung before getting to fb1 (the 3.5").

On the second reboot, both fb0 and fb1 were found, and Display Properties recognized the screen, but I couldn’t get it to activate/show wallpaper.

On the third reboot, I used only the 3.5" screen; boot text scrolled on the screen, and then it blanked as it normally does when entering the windowing environment… but it never showed up. I used Remote Desktop to access the system, and within the RDC client the representation of the desktop looked right. I tried the touchscreen and could interact with icons and the workspace even though the physical screen was blank. When shutting down, as soon as it “exited” the windowing environment the console/text shutdown messages started scrolling on the screen.

This is only one data point, and I didn’t dive any deeper to see if I could diagnose and tweak it to make it work. You might have better luck with your display, or you may hit similar roadblocks.

I’ll keep an eye out for any updated releases with fixes from Libre and try it again someday.

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