7" Wavehare display v2.1 on RK3328 running Ubuntu Server

Hello! Everything’s in the title. I’m trying to use a 7" Wavehare HDMI capacitive touch screen on the Renegade running the must recent Ubuntu server image.

It’s this model of screen: 7inch HDMI LCD (C) (Firmware Rev 2.1) User Manual - Waveshare Wiki

I’m just looking for display, touch functionality is not important to me.

Currently, the screen just flashes once at the beginning then turns white.


Hey @agilly I have seen this happen with a bad HDMI cable. I would verify all your cabling and perhaps replace

ROC-RK3328-CC display support is tested to standard resolutions like 720P, 1080P, QHD, 4K. If you want to use this screen, we recommend using Le Potato.

I thought the same and tried a different cable that works on a regular uxga monitor. The monitor and the cable work with the renegade, but not when I connect the small screen.

Also I tested the screen and original cable on a Windows machine and it works perfectly.

Does that mean that there is no way to use this particular screen? Is it just a resolution problem, in which case is there a way to change it somewhere in the system? Alternatively if this screen really is a no go, are there other mini screens compatible with the renegade?

Driving different HDMI screens requires the ability to generate different clock frequencies accurately. These SBCs do not have very complex clock generators like desktop machines. That’s not to say that the necessary clocks cannot be generated.

It is that these resolutions are so rarely used for this device that the driver may not support generating the right clock for the display. There’s is the possibility that the clock cannot be generated accurately as well.

All right. I don’t mind trying to configure the driver for this screen but I don’t really know where to start. Is there some documentation you could point me to?

Also, if this is just resolution dependent, any 60Hz 720p screen using hdmi should work out of the box, right? Which means I could always try with another mini screen with the right characteristics.

It turns out there are not a lot of mini displays with 720p or 1080p resolution (almost none actually), which kind of makes sense, at those sizes text would probably be horribly hard to read and need upscaling. So if anyone has any idea on where to start to try and configure the relevant driver for my existing 1024x600 display?