# HDMI Splitter Circuit...

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#### Promocom

##### New Member
I have a bluray player that I want to split to 4 rooms and I need a circuit or an IC or a method of splitting the signal. I found info on switching an HDMI signal but nothing on how to split it. I know I can just buy one but I want to hook up other stuff and control it with an arduino or something.

#### ronsimpson

##### Well-Known Member

These are all overt the internet. I have some.
"HDMI SPLITTER"

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#### Promocom

##### New Member
Yes like that one, I want to build my own and I would like to see inside or see the datasheet or know the chip number that this splitter or one like it uses...

#### ronsimpson

##### Well-Known Member
When I designed these things I used a HDMI receiver.
That gets you to "TTL" signals.
Then use 4-HDMI transmitters.

So I convert from HDMI to TTL and then 4x(TTL to HDMI).

This is not a bread board project. Must be on a PCB. The trace lengths must be the same for each signal. The high speed traces are transmission lines. This borders on RF.

#### Nigel Goodwin

##### Super Moderator
Yes like that one, I want to build my own and I would like to see inside or see the datasheet or know the chip number that this splitter or one like it uses...
Buy one, you couldn't build one for anywhere near the cost - assuming you could even source the special IC's required.

It's not a simple 'splitter' it has to take care of HDCP as well, or it won't work with many items.

#### crutschow

##### Well-Known Member
HDMI has up to 340MHz digital signals on multiple wires.
Definitely not a do-it-yourself project.

What you apparently want is an HDMI matrix switch which allows selection of multiple inputs to multiple outputs.
These generally have a remote control.
I'm sure with some ingenuity you could configure an "arduino or something" to generate those remote signals.

#### Nigel Goodwin

##### Super Moderator
So does that provide HDCP?, it doesn't appear to mention it?.

#### spec

##### Well-Known Member
So does that provide HDCP?, it doesn't appear to mention it?.
Not sure- I'm no expert on the subject.

spec

#### crutschow

##### Well-Known Member
Getting a schematic for the circuit is the easy part.
Building it and getting it to work properly is the fun part.

#### Nigel Goodwin

##### Super Moderator
Getting a schematic for the circuit is the easy part.
Building it and getting it to work properly is the fun part.
Depends what you mean by 'fun'

Spending a LOT of time and money recreating an existing cheap item isn't something I would class as 'fun'

But even the schematic above is only a small part, and requires a processor (and software) to control it - not to mention (yet again) no suggestion that it does HDCP, making it useless for any normal domestic use.

#### schmitt trigger

##### Well-Known Member
Never done a HDMI splitter, but I once did a LVDS splitter for several LCD screens.

Even though the display resolution was moderate (XGA 1024 x 768), the problem described by Crutschow, of properly dealing with multiple differential digital signals in excess of 100 Mhz proved to be a very tough nut to crack.
Without a proper analyzer ( \$) to measure skew and jitter, the color bleed would look horrible. In some instances the video would completely loose sync.

We had to ensure that every single signal path to be as identical as possible. Took several iterations of expensive boards.

Not a project for the faint of heart or budget minded.

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