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TV_Text pins? — Parallax Forums

TV_Text pins?

jmspaggijmspaggi Posts: 629
edited 2010-09-08 05:50 in Propeller 1
Hi all,

I'm using TV_Text to display text on a NTSC screen.

So far, I'm using 3 pins for that.

Do I really need to have 3 pins? I tried to deconnect them 1 by 1 but I lost the display each time. I tried to connect them to ground with no success.

Do I have a way to reduce that number? Or I really need those 3?

Thanks,

JM

Comments

  • tonyp12tonyp12 Posts: 1,951
    edited 2010-09-07 18:44
    Have to use special driver
    http://obex.parallax.com/objects/480/

    Debug to TV using 1-Pin
    http://obex.parallax.com/objects/578/
  • jmspaggijmspaggi Posts: 629
    edited 2010-09-08 03:32
    OK, but here it's reducing the number of colors or the size of the font...

    Look like I will have to keep my 3 pins ;)

    Thanks,

    JM
  • localrogerlocalroger Posts: 3,452
    edited 2010-09-08 05:31
    You need the 3 pins because they are used as a crude digital to analog converter via the 3 different resistors (and the implied 75 ohm impedance of the video input you're feeding). This allows the prop video circuitry to create 8 output levels, and in particular the color burst circuitry really assumes that you have that divider network; without all 3 pins it won't work at all.

    The 1-pin video driver uses a different technique with the counter/timers to do crude DAC but it can't do color burst, so it's B&W only.
  • jmspaggijmspaggi Posts: 629
    edited 2010-09-08 05:50
    OK! Got it!

    It's still a good information to have since I might have to use the same screen as a debug device, so I will use the 1pin driver.

    For now, this will be a MP3 player for my car, so I will keep the 3 pins and the colors.

    Thanks,

    JM
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