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Atlys HDMI J2:OUT voltage question.


chcollin

Question

Hi,

I am facing a strange issue with HDMI output on Atlys J2 connector, hope someone will help me understand.
J2 outputs a 720p signal @74.25MHz, based on a modified version of HDMI Demo hdmi_out (I'm using an external clock instead of the 75MHz one in the demo).
Everything goes smooth with any casual hdmi cable.

However I own an active HDMI cable, from Marseille Inc. This active HDMI cable (called mCable) is a 1080p upscaler with anti-aliasing and sharpening processor.
Unfortunately, when using this cable I get no signal on my TV set.

I wrote to Marseille Inc support, here is literally their answer :

Please try provide 5V(pin18), pull up to 5V on DDC lines (pin15,16) on the RX side of mCable.
mCable won't operate if it does not see 5V from the source side.
And low DDC line could cause mCable to hang up.

Note that my EDK project does not handle DDC handshake (nothing connected to C9/D9.
I thought maybe the mCable needed DDC handshake to catch EDID from the sink, but I doesn't seem to be the case.

So, could anyone tell me if J2 abides Marseille support prerequisites ?
Am I supposed to add C9/D9 to my scheme so that current is pulled up to these lines or does the Atlys do it anyway and it's a problem with current too low ? (but the way, I thought DDC was 3.3v and that 5v line was only to power EDID eprom on the sink... I must have missed something).
N.B : JP6 and JP7 are unloaded, don't know if it has something to do with this problem, I doubt it.

Thanks very much to anyone helping me.

Regards.

Edited by chcollin
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