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iphone to hdmi question 
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Joined: Sun Jun 30, 2013 1:18 pm
Posts: 8
Real Name: Kevin
i want to hook my iPhone up to my projector to share pictures and videos on a much larger screen. i know apple sells a converter for this purpose but it costs $40+. i already have an HDMI cable and a spare iPhone sync cable laying around. my problem is trying to figure out which wires to splice. i have found some pinouts for both cables but i don't understand the labels for the HDMI cable.

if you could help me decipher this that would be awesome!


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Tue Oct 01, 2013 7:35 am
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Joined: Wed Nov 28, 2012 2:48 pm
Posts: 58
Real Name: Dan
I'm no expert, but the little bit I know about HDMI is that it basically contains three high speed serial busses using differential signals (the TDMS lines). Differential signaling is used by high speed connections like USB, LVDS, and Ethernet and it sends data using two pins instead of one. Doing that helps electrically to fight signal noise, crossover, etc when data is moving at really high speeds or is going through long cables.

The other things on the HDMI pinout (DDC and CEC) are used for querying the HDMI device to figure out its capabilities (supported resolutions, preferred timing characteristics, etc) and to control devices (play, pause, rewind, etc).

As for which pins to connect to an iPhone connector, I think you might be in for a bit of a challenge. From looking here, it seems that the 30-pin connector has video out, but it's either composite video or S-Video, both of which are analog video signals, not HDMI natively. That means you would need an 'active' connector, which is capable of not just hooking wires on one connector to the other, but actually converts the data from one format to another before passing it along. That seems to be supported by sites like this one that describe thin circuitry that can fit within the iPhone to HDMI connector cables.


Wed Oct 02, 2013 7:00 am
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Joined: Sun Jun 30, 2013 1:18 pm
Posts: 8
Real Name: Kevin
thank you. i guess i will be buying the $40 dongle from apple.


Wed Oct 02, 2013 5:19 pm
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Joined: Wed Nov 28, 2012 2:48 pm
Posts: 58
Real Name: Dan
If all you're looking for is a cheaper converter, there appear to be third-party options: this one, for example.

If you were hoping for a project, though, you might still be able to do something if you don't mind composite video output instead of HDMI.


Thu Oct 03, 2013 6:31 am
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Joined: Sun Jun 30, 2013 1:18 pm
Posts: 8
Real Name: Kevin
i was just wanting to make my own since i had the extra cables on hand. i already ordered one from amazon, should be here today.


Fri Oct 04, 2013 6:52 am
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