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Help undestanding TMDS

  1. Oct 10, 2012 #1
    Hi my names Dom, just joined the forum and look forward too getting to know you other members.

    Hopefully i've posted this in the right section.

    I'm struggling to understand a TMDS datasheet and was hoping someone with a bit more know-how could help me out (draw it in crayons for me) :D

    I have a source device that outputs three 8bit serial RGB lines aswell as clock, Hsync and Vsync. I've read through the datasheet for a SIL150A TMDS transmitter/encoder and the pinout is confusing me.


    If i understand it correctly (unlikely) my serial 8 bit red signal would go to DIE23 Pin 90, green to DIE15 pin 99, and blue to DIE7 Pin 9 and this would give me 1-pixel clock input mode? input clock, HYSNC & VYSNC all seem pretty self explanatory to hook up (although i'm probably wrong about that too)

    If the above is correct? what are the outputs to the corresponding inputs.... for a DVI setup for example, is it TX1+ etc?

    Thanks in advance to anyone who can help out.

    Attached Files:

    Last edited: Oct 10, 2012
  2. jcsd
  3. Oct 11, 2012 #2
    Edit: above, seems as though the transmitter above can only output analog (i think) and not digital, hdmi, dvi which is what i'm after, but the same principles apply to other TMDS transmitters such as analog devices ADV7513
  4. Oct 13, 2012 #3
    I looked at the datasheet and it's pretty self-explanatory. :uhh:

    No, the inputs are parallel. You have to deliver the entire 8 bits for each colour at the same time (so for red you place a 8 bit value at DIE16-23. Check the Input Pin Description section in the datasheet PDF (p.4).

    No, PIXS held LOW sets 1-pixel mode.

    I don't know much about TDMS but it looks like it uses 4 differential pairs - TX0+/-, TX1+/-, TX2+/- and TXC+/- for transmission.
  5. Oct 13, 2012 #4
    The output is a digitally modulated signal, so the result is analog. That's Digital Communications 101.
    Last edited: Oct 13, 2012
  6. Oct 14, 2012 #5
    Thanks for your resposne, youve been a great help.

    I'll have a bash at it and report back :)

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