CVBS Out?

[Hyojae Kim]

Hello, I am going to use CVBS output but I can't find any documents to work with.
Does Anyone knows how to set display output as CVBS instead of hdmi?
I've already found CVBS pin and Ground, But that's all.

[István Nagy]

I think at least you should create a custom script.bin where you modify the disp_init values to the correct ones required for CVBS: http://linux-sunxi.org/Fex_Guide#12.1_.5Bdisp_init.5D You need the sunxi-tools to convert between fex and bin formats.

But that's only guessing from me because i haven't tried it myself.

[killwarez]

Config it script fex/bin for display output mode, connect to tv and add 75kOhm resistor.

[Hyojae Kim]

yeah. I set up script.bin through bin2fex/fex2bin and It works.

but why do I have to add 75kOhm resistor? CVBS works without it.

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[István Nagy]

Could you please post your modifications to the script.fex file? Just for the log :-)

[István Nagy]

[George Ioakimedes]

the 75 ohm resistor is a termination resistor used to set the impedance of the signal. video signals should be 75 ohms to avoid reflections. things will work without them but the picture will be better and more stable under different conditions with proper termination.

[Hyojae Kim]

75Ohm is the right resistor? isn't it 75kOhm? 

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[George Ioakimedes]

what schematic are you referring to?

[Hyojae Kim]

I just searched the forum.

[Filipe Santos]

Why not using something like this: http://www.monoprice.com/Product?c_id=102&cp_id=10236&cs_id=1023601&p_id=620&seq=1&format=2

Instead of soldering a separated 75 ohm ?

[George Ioakimedes]

Because you "need" the 75 ohm on the board/circuit to match the impedance. You can try without the 75 ohm resistor but depending on which cable and TV you connect you might not get results

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[Filipe Santos]

So i need a 75 ohm coax cable AND aditionally a 75 ohm resistor?

2013/10/30 George Ioakimedes <georg...@gmail.com>

[George Ioakimedes]

All video cables are 75 ohm by design.  If you can I would add the resistors

[cubie...@gmail.com]

Try turn on CVBS with HDMI at the same time.
First test CVBS from android screen settings. It works, but from HDMI signal lost.

Take script.bin from nand, convert to fex and edit

[disp_init]
disp_init_enable = 1
disp_mode = 4
screen0_output_type = 3
screen0_output_mode = 4
screen1_output_type = 2
screen1_output_mode = 11 (and try 3)


Connect to TV. Get black screen with short strob at the middle of screen.
Are you sure you need a 75 ohm resistor?
CVBS is no signal from the antenna or cable.