Making a reliable HDMI male-to-male

Discussion in 'General Electronics Chat' started by Domarius, Apr 14, 2019.

  1. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    My project involves connecting my Raspberry Pi 3 to a 5" HDMI 800x480 display. I want to make my own little cable to do it, and I bought some HDMI plugs off eBay that are ready to solder onto wires.

    I thought I could just wire them up pin to pin (making sure the wires twist over so they match up to the same pin on each head) but I just realised that there are different HDMI speed standards and I don't know what that means in terms of how a HDMI cable is made.

    Is there anything I should know before trying this? Just wouldn't want to ruin anything.
    This is the display; https://raspberry.piaustralia.com.au/little-bird-5-display
    And the model on the circuit board is XTP2046 (though I notice this will give search results that show other types of display that use the same chipset)
    (The display supports mounting the Pi directly onto it, and I've been doing this for testing, but this arrangement won't work for my actual project)
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    4,529
    718
  3. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    Thanks for the video. Maybe I could've worded the question better - I already have my own materials (ribbon cable, and HDMI plugs) my question was really about in what way HDMI performance is affected by the materials and make of the HDMI cable. I'll just go ahead and try it :)
     
    Last edited: Apr 14, 2019
  4. shteii01

    AAC Fanatic!

    Feb 19, 2010
    4,529
    718
    HDMI signals are digital. So basically, whatever you make, it will either work or not. The only thing you can truly affect is shielding (and maybe stray capacitance).
     
    spinnaker likes this.
  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589

    Buy a cable. They are very cheap and the price is not worth the headache.
     
    Tonyr1084 likes this.
  6. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    Thanks :) That's re-assuring. I'll go ahead and wire one up.

    The reason I'm wiring one up is it's a very small project, I don't have the space for a cable with its huge long plugs. Below is the design - I've hidden the outer casing, and I've circled where the HDMI output is on the Pi, and where the HDMI input will be on the display (at the top of the screenshot, haven't modelled it in yet)
    upload_2019-4-16_7-26-32.png
     
  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    4,345
    1,603
    Ummm... buy the cable. I can’t tell you how many video installs I’ve been involved in which failed until we purchased a commercial cable. Video signals are very sensitive and any teeny tiny minuscule deviation in the cable will bollix things.
     
    spinnaker likes this.
  8. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589

    What do you consider a "huge long plug". I have one here that is not much more than a milometer. Bet you could cut away the case and make it even smaller. HDMI connectors have 19 pins. The chances of you wiring that up successfully are awfully slim and certainly an enormous headache. I would consider changing my design.
     
  9. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    Well I'm using a ribbon cable, so it should just be a matter of twisting it before soldering it to the other plug (1 ribbon for each side of the plug of course). But if that fails I will look into buying a cable and cutting away the case. As long as it just "either works or doesn't", and I don't have a risk of ruining anything, I'm willing to give it a go.
    I don't have a lot of room to work with, it's meant to be a fake mini computer to play retro games and watch 4:3 videos on. Increasing the height of the "monitor" case would mean increasing the size on all sides to keep it even looking and the monitor bezel is already looking disproportionately thick to hide the width of the actual display.

    upload_2019-4-16_11-56-19.png

    The display and Pi are housed in the "monitor area" and it's self contained. You can optionally plug on the base, and it has speakers in it, an external HDD, and room for a potential power pack to make it portable, if I want to spend money on it.
     
  10. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589
    At the very least buy a cable and chop off one end. That way you only have one end to worry about. You could use something like a terminal block at one end.

    I love these.
    https://www.ebay.com/itm/20pcs-KF30...m59220da3ec:g:2uMAAOSwklxcfw0T&frcectupt=true

    And if you don't have space for that then solder the wires on to a PCB or solder to your ribbon cable. .


    Before you chop off one end be sure to test the cable on your TV or monitor. ;)
     
  11. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    How would the terminal block be used? I've never seen one...
     
  12. Yaakov

    Well-Known Member

    Jan 27, 2019
    1,198
    584
  13. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589
    Last edited: Apr 17, 2019
  14. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589

    See what I posted. You can solder them right to your PCB just like any other component. Though with as many wires as you have for a HDMI cable they might take a bit of room length wise. And now I think of it, I also might be concerned about getting the wires that far from their shielding.
     
  15. Yaakov

    Well-Known Member

    Jan 27, 2019
    1,198
    584
    It was an unfortunate case that there are terminal blocks in that connector. I wasn't pointing at them for the terminal blocks but for the connector aspect.
     
  16. Lo_volt

    Member

    Apr 3, 2014
    17
    4
    My experience says that soldering ribbon cable is not a task for those with little experience when it comes to soldering. The insulation melts, deforms and burns at way too low temperatures. I wish you luck at your efforts in the attempt.

    In the event that you get frustrated with soldering your own cable, check out this offering from monoprice.com:

    https://www.monoprice.com/product?p_id=13586

    It comes in lengths as short as 0.5 ft, and the connectors are not particularly bulky. No endorsement of their products, it's just something I found that sounds like it might work for your project. You are welcome to search for something else as well.
     
  17. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    7,785
    3,589

    But actually kind of a cool connector if it actually works. It would save the nightmare of trying to crimp your own connector.
     
  18. Yaakov

    Well-Known Member

    Jan 27, 2019
    1,198
    584
    It could be very handy indeed.
     
  19. Domarius

    Thread Starter Member

    Sep 1, 2013
    21
    1
    Ok, it didn't work, heheh. I think I did a pretty good job - it wasn't easy, it took about 3 hours, and fixing mistakes, but I got every pin soldered up to the ribbon cable neatly, the ribbon was twisted so that the pins match up of course, and I tested for no continuity between every adjacent pin - all seems good. Fired it up, and after flickering a few times, the display stated "Not support". Oh well.

    Thanks for the suggestions guys. Well, since my DIY cable is "Not support", I guess I'm going to look at hacking apart a real one. I was thinking about buying this one and dismantling one of the plugs to get it to fit into that tiny space above the display.
     
  20. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    4,345
    1,603
    I meant to comment on using ribbon cable. Ribbon cable carries and/or attracts too much interference to use for video.
     
Loading...