Thanks for your detailed reply. That means hdmi source working like opendrain gpios, so I should to provide the Vcc power to probe its signal. But I find some hdmi circuits picture which the source also provides 3.3v pullup, maybe there are some different versions of hdmi source designs.you wont get anything, due to how hdmi worksif you disconnect monitor, Can you probe the hdmi signal on the port with logic analyzer?
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the source (rpi) will pull one side of the differential pair low
the sink (display) has pullup resistors, and measures the difference
with no display, you have no pull-up, and both lines will register as low
Statistics: Posted by dsds — Mon Mar 25, 2024 7:23 am