Compute Module • Re: Why does HDMI on my CM4 Carrier board work on 1080p monitor but not my lower res 7" touch screen

You haven't really paid any attention to the PCB layout notes for the HDMI signals in the CM4 datasheet. You haven't connected the CM4 grounds. Have a look at the cm4io board .

I didn't think about the Impedance but I did length. And I cant believe I forgot to ground those pins... I did get the other high speed connector. First time blunders.

Is the impedance and ground issues enough to stop some displays from working?

Statistics: Posted by lightofice — Sat Apr 12, 2025 11:15 pm

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