Noise on DisplayPort high speed lines when using the AUX connector

[mithro]

When Mike tries to use the AUX channel on the DisplayPort connector, it causes the high speed link to drop. We are currently investigating;

From Mike;

Whenever the link is up and stable:

• If I leave the AUX channel tri-stated then the link stays up.
• if I waggle the AUX channel to ask the sink for it's status I get the main links drop,
• There is high frequency 'noise' on the AUX channel when tristated
• If I drive the AUX channel to 0 or 1 when idle the link doesn't come up.

This is quite probably a side effect of #9 -- but we need to confirm.

[mithro]

@hamsternz said;

Tested for a short with a scope and couldn't see anything (watched the lanes while AUX EDID probes were going on).

[mithro]

As the repository has moved forward, I've uploaded an older version of the schematic for the preproduction boards at https://github.com/timvideos/HDMI2USB-numato-opsis-docs/blob/gh-pages/pdfs/NumatoOpsis-schematic-v2-prototype-13-gb1c4312.pdf

[mithro]

Oh wait, that version is still too new. It has the decoupling capacitors. Will need to go back further.