Go Down

Topic: Arduino to switch HDMI on/off ??? (Read 5 times) previous topic - next topic

red_car

Aug 24, 2012, 05:06 am Last Edit: Aug 24, 2012, 05:10 am by red_car Reason: 1
Hi all

Looking for a little expertise from the forum gurus...

I would like to use an Arduino UNO to control whether an HDMI signal can be sent over a cable.  The UNO would sit between the HMDI source (PS3) and receiver (TV)... and depending on certain conditions will either allow the HMDI signal to pass through or not.

I know that HMDI cable contain a number of channels for various things over 19 separate wires.  Is there one of these that I could isolate that would have the desired result ?  I was antipcating some surgery to the cable.

Any ideas around a possible circuit that could be used to acheive this (i.e. UNO PIN high allows pass through, UNO PIN low blocks signal) ?

Thanks in advance for your help.


Far-seeker

#1
Aug 24, 2012, 05:49 pm Last Edit: Aug 24, 2012, 06:34 pm by Far-seeker Reason: 1
If you only want the Uno to control the connection, you don't need to feed any of the wires from the HDMI cable into the Arduino.  Instead, you'd have the Uno control some appropraitely rated transistors (one for each wire) setup as simple on/off switches.

Edit: If you aren't that familiar with electronics this is the type of circuit I'm refering to, again you'd need one transistor per wire in the HDMI cable.  Depending upon the exact type of transistor you use, it might be possible to use only one pin from the Arduino to control all the transistors. The only limiting factor would be the total current draw on that pin, but if the current drawn per transistor is less than 1.5 mA then it should be OK.

red_car

#2
Aug 24, 2012, 10:20 pm Last Edit: Aug 24, 2012, 10:23 pm by red_car Reason: 1
Thanks for the reply.

Do you think I could get away with doing this to just some of the wires within the cable?  I presume that some of them are more critical than others for sending the video signal?  Any ideas on the minimum number I would need to block to effectively turn off the signal?

Thanks.

Far-seeker


Thanks for the reply.

Do you think I could get away with doing this to just some of the wires within the cable?  I presume that some of them are more critical than others for sending the video signal?  Any ideas on the minimum number I would need to block to effectively turn off the signal?

Thanks.


I don't know for sure, it would depend the purpose of each wire and I'm not familiar with any of the details for the HDMI standards and specifications.  My advice is plan to use a MOSFET for each contact.  Keep in mind though, there are ways to tie them all together so they could all be switched at the same time and probably with just one digital pin.

Also have you looked for HDMI connectors?  You'll need two and buying them, even at low volume prices, is going to be significantly less expensive than sacrificing a store bought cable.  If you can find ready-made break-out boards (especially populated ones) that will make things easier still.

MichaelMeissner

#4
Aug 24, 2012, 11:28 pm Last Edit: Aug 24, 2012, 11:36 pm by MichaelMeissner Reason: 1
One alternative is to use an HDMI switcher.  You can get these cables for $5-10 from Hong Kong merchants.  Here is the cable sold by an Amazon reseller: http://www.amazon.com/SANOXY-Switch-Switcher-Blu-Ray-HD-DVD/dp/B0040G5KY6/ref=sr_1_2?ie=UTF8&qid=1345843556&sr=8-2&keywords=hdmi+switch+boxes

I would imagine if you open the box, it should be fairly easy to have the arduino control the switcher by simulating the button press with an opto-isolator.

Then you can switch from the live cable to the 2 other cable slots.  If for some reason you don't want to open (and possibly destroy) a $5 box, you could always use a servo to press the button (but then this forum is named device hacking).

In terms of HDMI breakout cables, I did a google search, and the first link wanted $60 for the breakout box, and it only seems to give you the DDC information (http://www.totalphase.com/products/video_hdmi/).  However, given the Arduino is generally too slow with limited memory to deal with normal video, it would probably be like drinking from a firehose to keep up with hdmi.

Go Up