4 Inch Screen Compatibility -

#1

I have a wave share 4 inch tft touch screen: waveshare 4 inch HDMI LCD IPS Display 800x480 Resolution Resistive Touch Screen Interface for Raspberry Pi 4 B/3 B/3 B+/2 B/B+/B Zero W https://a.co/d/dT3W7yR

I also have another 7 inch touch screen that is working totally fine, I have logged into the RPI4 no problem with this. However the 4 inch screen does not display anything, no errors, no text, etc.

I followed this guide for the waveshare 3.5: https://wiki.radxa.com/Rockpi4/hardware/display
But the 4 inch screen stays blank, when I plug the 7 inch screen back in, there is an error after I rebooted. Has anyone ever set up one of these displays on the rock pi 4c+? Pictures of the screens and error attached.

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5E906AAD-3AFC-4EC8-A086-F990E4674B9F.jpeg4032×3024 3.31 MB
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C150ED1D-33EB-48C2-AC04-1E3CCAB8DF21.jpeg4032×3024 3.42 MB

#2

I also have another 7 inch touch screen that is working totally fine

do you means the 7 inch touch screen work fine on rock pi 4c+ ?

For i4 Inch screen ,does it stay blank or error every time ?

#3

Thank you for the response, it just stays blank, doesn’t appear to try and display anything.
Last night I connected both displays with a fresh install and when I looked at the display configuration, it seems like only the 7 inch display is detected, hope that helps.

#4

so the issue is below ,right ?

  1. the 4 inch display can’t be detected on both HDMI interface of rock pi 4c+
  2. the 4 inch display can be detected and can work well on PC or RPI, but can’t be detected on
    rock pi 4c+

can you show the kernel log when you plug the 4 inch display on board ?

#5

Hey Peter, sorry for the late reply, I’ve spent some time and I can’t seem to find the kernel logs on this Debian installation provided, I checked var/log/messages, kern.log, and syslog but no luck… thank you. Do you know where they are on the radxa builds?

#6

you can execute dmesg on the terminal like this to capture the logs

#dmesg > dmesg.log