From what I recall its not really HDMI, but DVI-D through an HDMI connector.


My bet is its not software, but just a bad solder connection on the TFP410 chip that does the Digital to TMDS conversion. Or somehow the edge selection is misconfigured on your board (doubtful).


You’re using a known good GNOME build, cable, and you’ve tried multiple DVI monitor so its probably just a bad board. Does the DVI monitor correctly report the resolution you’ve set? You’ve also tried the Sakoman drive image, and never built anything or changed anything (until you testing changing the resolution)? Just did a DD image copy?


If all that is true then I’d check to make sure the resistors that had to do with de-skew, clocking edge were stuffed properly. From what I recall on the TOBI all the TFP410 settings are set by resistors.


From: David Diel []
Sent: Friday, April 27, 2012 11:41 AM
To: Blaine Booher
Cc: General mailing list for gumstix users.
Subject: Re: [Gumstix-users] HDMI noise with Overo FireSTORM / Tobi / GNOME daily build


To clarify a couple of issues:

The GNOME build is version r13, Linux version 3.0.0.
The boards were delivered two days ago directly from Gumstix.
The monitor used for the illustration was a HDTV.
The screen appeared blank when connected to a different monitor's DVI-D input.
Changing HDMI cables had no effect.

On 04/27/2012 02:19 PM, Blaine Booher wrote:

Since HDMI is a digital signal, this would imply that signal on your line would cause a scrambled image. That means that the noise isn't coming in from the hdmi signal itself... it's either being fuzzed at the connector end after digital to analog translation, or the noise is being converted before the hdmi signal is being generated, and then sent to the monitor entirely...


Hmm. That's tricky. I'm curious to see where this goes.

Blaine Booher

Clifton Labs, Inc

(513)-400-5606 (work)

(937)-570-9336 (cell)



On Fri, Apr 27, 2012 at 2:09 PM, David Diel <> wrote:

I have a problem with some serious HDMI noise from the Overo FireSTORM /
Tobi expansion board, illustrated by the following image:

I loaded a 16GB Class 10 MicroSD card with the Sakoman GNOME daily
build, booted several times at different resolutions, tried different
HDMI cables, connected to different monitors, and I've still got random
streaking and discoloration.

Can anyone tell me whether this is a hardware or software problem?

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