Finishing up the hardware

Discussion in 'Pyra News' started by EvilDragon, Jun 20, 2015.

  1. TrashyMG

    TrashyMG Sarcasm Dispenser Staff Member

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    For one the LCD connection is completely different the Pyra uses a MIPI interface. While the devboard and the SoC may have the connections to drive another display I doubt these connections will be brought out from the CPU board as the amount of connections needed are a lot (60 traces to be exact from the PDF of the Pandora LCD).


    Also you haven't even seen the 720p 5" Pyra screen in action and you are already wanting to replace it with a smaller lower resolution 800x480 screen?
     
    Last edited by a moderator: Jul 2, 2015
  2. Hồng Thất Công

    Hồng Thất Công Đả Cẩu Bổng Pháp

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    Not at all.  All I was saying is it would be nice to be able to hook up the Pandora screen as the second screen.  Of course I like the Pyra 720p screen as the  main one.
     
  3. Grench

    Grench Forum Addict!

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    12mA is what the rotator chip can consume from it's power line voltage.
    That says nothing about the actual signal strength coming in and going out. I suspect those may have needed to be wider traces to decrease signal weakening as it's going through this bit-sorting-rotation chip instead of straight to a display?
     
  4. levi

    levi Still fresh, damnit!

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    I don't know exactly how the rotator chip works, because apparently it doesn't store the incoming picture in a framebuffer then squirt out the rotated image, but I expect it'll have to have some sort of buffer as you can't assemble a full rotated line until you've received most of the frame.  So therefore, I'd expect the signal to be regenerated from source voltage.

    Or on the other hand, it's possible that you might be able to rotate a video frame a little like you can rotate JPEGs; by setting a couple of bits in the header.  In which case it's possible it might be assembled using some sort of relay to connect the output lines up to the input lines once it's fiddled with the header, but I've never come across a solid state device containing a relay, so that's unlikely.  More likely it uses a series of logic gates which result in the signal again being regenerated, so that 12mA would include the power needed to run that logic.
     
  5. ssokolow

    ssokolow Member

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    The Pyra has HDMI and USB ports, so why not just grab one of the many touchscreen LCDs meant for hacking together Raspberry Pi-based gizmos?


    I don't have a site for resistive touch bookmarked at the moment, but this site'll give you ready-made 1280x800 stuff for capacitive touch in the 7" to 15.6" range:

    http://www.chalk-elec.com/?page_id=1280#!/HDMI-interface-LCD-+-touch/c/3094861/offset=0&sort=priceAsc


    (I was thinking of making something sort of like a wired iPad but fully open and then mounting it on an arm near my bed. At least one model even offers an ambient light sensor for automatic brightness control for a few extra bucks.)
     
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  6. TeDaDeS

    TeDaDeS Very Active Member

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    ED posted this:

    "Apparently the LCD cable and some traces were too thin for the power needed, which was a good guess."

    So the question would be, how small are the traces that they couldn't handle 12mA. Pretty small or the fab couldn't accurately produce this kind of small pitch.
     
  7. rygD

    rygD Nihilistic Mystic

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    I knew someone with an interesting little portable display that folded up.  I think it was around 7 inches.  He used to connect it to whatever computer I saw him using, however I think he had it since he liked having 2 displays even when he was out with his laptop.  I prefer to have multiple displays as well, but I usually resort to just using multiple virtual desktops and shortcut keys to bounce between them.  Sometimes I need to see 2 things at once, and window transparency comes in handy there.

    Before I go off on a tangent, I will try to find the one this guy had.

    Edit:  It was one of these foldable ones:

    http://www.mimomonitors.com/collections/7-inch-monitors
     
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  8. WizardStan

    WizardStan Mega GP Mania

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    Given that the result of the small traces was broken image I'd suspect that the problem was the data lines not being able to transmit the amount of power needed for a clean signal, not the power line being too thin to keep the chip alive.
     
  9. TeDaDeS

    TeDaDeS Very Active Member

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    Quote from same post:

    "Nikolaus checked the hardware and found out that the voltage for the solomon chip was too low."
     
  10. WizardStan

    WizardStan Mega GP Mania

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    The voltage isn't the power though. Not sure what's being discussed, what the actual problem was.
     
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  11. levi

    levi Still fresh, damnit!

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    Yeah, but if a trace is too thin, its resistance will be too high, dividing a voltage across it and resulting in less for the chip.

    Edit: If the chip tries to draw too much current (current=power/voltage) then the resistance of the trace will cause more voltage to be lost across it.  That's what happens if you try to pull too much power - resistances outside your circuit come into play and the voltage drops.
     
    Last edited by a moderator: Jul 3, 2015
  12. Natsu

    Natsu Advanced Member

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    Sorry, tab mixed up and not to mention my browser keeps crashing. Time to close some tabs. Lol
     
    Last edited by a moderator: Jul 24, 2015

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