Friday, April 05, 2013

VGA out for cubieboard

Because my TV is used mainly for watching. I need an alternative display output for my cubieboard. The easiest way is using CVBS pin, and attach it to RCA jack to connect to video input. But I don't have another display with video in, so I need to built VGA out for the cubieboard.

Component needed :
  • 3 x 75 ohm low-tolerance resistors.
  • 1 x 74ACT08D quad AND gate.
  • 2 x bat54s SCHOTTKY diodes (I can't find it in my local store, so I change it with 4 x bat85s or any SCHOTTKY diodes).
  • 1 x 100 nF low-tolerance capasitor.
  • 1 x VGA DB15 connector.
Schematic from olimex :


script.bin:

[disp_init]
disp_init_enable = 1
disp_mode = 0
screen0_output_type = 4
screen0_output_mode = 4
screen1_output_type = 2
screen1_output_mode = 14
fb0_framebuffer_num = 2
fb0_format = 10
fb0_pixel_sequence = 0
fb0_scaler_mode_enable = 1
fb1_framebuffer_num = 2
fb1_format = 10
fb1_pixel_sequence = 0
fb1_scaler_mode_enable = 1

after everything ready, you can turn on your cubieboard on a monitor with VGA jack. If everything went right, the output should be displayed in your monitor.

Here you can see the picture of working vga out in cubieboard using ubuntu image from miniand.com :

cubie_vga1
cubieboard vga out 1

cubie_vga2
cubieboard vga out 2
Sources:
http://www.cubieforums.com/index.php/topic,104.0.html
https://groups.google.com/forum/#!msg/cubieboard/vSdUzKoY6S0/AL6kuShCdCIJ

20 comments:

Anonymous said...

Is it possible to use pins 33 and 35 for HSYNC/VSYNC?

arieedzig said...

As far as I know, pin 33 and 35 are for LCD HSYNC/VSYNC. So it will not possible.

Anonymous said...

Hi, I have one question. Where do I connect the 3 pins of +5v? External supply? I do not see that in your images.

Thanks.

arieedzig said...

Hi,

I use pin 1 U15 for +5v and pin 25 U15 for ground. But I think you can use another pin which have +5v or ground.

wisnu hidayat said...

Hi,

I'm planning on buying a cubieboard, but I wonder if this VGA stuff will work with pre installed android version?
I see the screen shoot says it was Ubuntu not Android, so which setting should I change on the android?

Since I have only VGA monitor and don't have any HDMI monitor, will it be some ways to edit the setting?

arieedzig said...

I never tried using pre installed android, but it works with Android TV Box Allwinner release 2 image. But I think, the pre installed image uses the same source code, so theoretically it would work. But the setting is a little bit complicated because the android uses an automatic display configuration. I saw in the code that the display (the default is HDMI) will switch to another display when we plugged in another display (such as VGA monitor) but when I tried, my monitor was only display a black screen even thought it detect there is some signal. I think that was because of the default resolution of VGA. So I change the resolution from android setting using the screenshot displayed via ADB Tools. It succeed but a little bit complicated or you can change the setting first in HDMI monitor (borrow it from your friend). Don't use image Release 2.2, because it cannot save the change we have made to the display setting configuration. Another way, you can install an image from Silverio Diquigiovanni as mentioned on this forum and change the script.bin and script0.bin as in my configuration.

Anonymous said...

Hi I have a question about script.bin.
This is my first experience with cubieboard and linux then I suppose my question can be trivial.
I have a baseboard and I connected the cubieboard, now if I want to use the VGA connection, I need to create a script.bin files with the instructions declared on top.
The question is: what is the pat for the script.bin file?
Are need other actions to use the VGA connection for the cubiboard video output ?
Thanks

arieedzig said...

If you work with android, you should mount /dev/block/nanda, you will find the script.bin in that partition. This partition is not mounted automatically, so you need to manually mount it. If after you changed the script.bin, still no output to VGA, you should consider to use android image from Diquigiovanni as I mentioned on the previous comment.

Anonymous said...

I use Debian, I think it is similar to Ubuntu.
I saw on images on top you can redirect the output od ubuntu on VGA.
I searched on file system but I do not found any script.bin.

arieedzig said...

If you use sdcard, try to get it from /boot (mounted from /dev/mmcblk0p1) if you cannot find the script.bin, the file could be named as evb.bin. Normally, you can find the file on the fat partition of the sdcard, so you can get it without boot to the system.

Anonymous said...

ok now work fine.
I mounted the microsd with a card reader, I found the script.bin files and I changed the settings.
Thanks for your help

Ciao

VGA Switch said...

So one will need to use a chip to convert the levels to VGA-HSYNC / V-SYNC by help of various pins. Well, thanks for the post!

d@le said...

Hi

Is there any alternative for this 74ACT08D IC?
I can't get it in my country :(

Please help

arieedzig said...

I am not sure about this, but this is a quad AND gate IC, maybe you could try to use another quad AND gate which have the same characteristic if you couldn't find any, just check the data sheet, though, I got SN74LS08N IC from my local store.

USB Extenders said...

Looks like some real good work. I've been using the same VGA circuit and have not been able to get an image.

arieedzig said...

Which operating system do you use?I suggest you to use linux, because with android tvbox, you need an additional complicated configuration with the display settings. Normally the problem is with the script.bin, have you tweak this file?

Filly said...

How can i connect the cubieboard to an S-Video input?

Any suggestions`?

arieedzig said...

As far as i know, cubieboard only has cvbs/tv-out/composite expansion header. It is in pin 43 U15, some of people said that you need to add resistor between the pin and ground, but it will work also without resistor.

Samudera Al Hakam said...

Hi there,

From my little knowledge about digital electronics (I'm an EE student btw), the quad AND gates apparently just function as buffers as the output is the exact same logic state.

Do you think replacing the quad gates with buffers will also do the trick? Just being curious

Btw, greeting from fellow Indonesian ;)

arieedzig said...

Hi, sorry about that. That is beyond my knowledge, but you can do the experiment if you want :-D.