Hello,
i really want to buy a A13-OLinuXino-MICRO but one question remains.
Can i configure the vga output for CGA like resolutions, 320×224 for exemple ?
It is for interfacing an old arcade crt tube to the card (15khz).
Sorry if this is a 'i want it all and i want it now' question but i'm pretty new to Arm world.
I will use the fb only, so i cannot use Xorg config file for resolutions.
Thanks for your attention.
Florent
EDIT = of course composite output is not an option for me, i want RGB.
I think that it can be done.
I think that you have to modify the parameters lcd_x, lcd_y, lcd_dclk_freq, lcd_hbp, lcd_ht, lcd_vbp, lcd_vt in script.bin ( take the script bin for the vga 800x600 as a starting point ).
thanks for the tip, i'm also looking at source code of uboot, there is a lot of interesting parameters in it ..
Now i'm looking for converting modelines into uboot parameters ;D
Looks like it is time to buy this "little toy" ^^
I don't understand how to tell to the A13 to output 15khz hsync with lcd options .. is it possible ?
i've read that vga out is a beautifull hack of lcd output, so this option may not be present ?
Check the fex guide http://linux-sunxi.org/Fex_Guide#lcd.5B0.2F1.5D_configuration (http://linux-sunxi.org/Fex_Guide#lcd.5B0.2F1.5D_configuration)
I think ( I have not tested myself ) you can set something like this ( or at least this is a starting point ):
lcd_dclk_freq=5 // 5MHz
lcd_x=320
lcd_y=224
lcd_ht=333 // this should give you a 5MHz/333=15KHz horizontal sync
lcd_hbp=6
lcd_vt=452 // vysnc total cycle * 2, this should give you a 66Hz vertical sync
lcd_vbp=1
thanks for the tip, i will try it next week (postmail please go faster :) )
but .. i don't understand=
lcd_ht=333 // this should give you a 5MHz/333=15KHz horizontal sync
How do you calculate that ? :x
Quote from: dapsaille on November 06, 2013, 10:41:30 PM
lcd_ht=333 // this should give you a 5MHz/333=15KHz horizontal sync
How do you calculate that ? :x
with a calculator... or even with a piece of paper and a pen, I'm old school ;-)
hahaha ;D
sorry for that stupid question .... i was tired ::)
You can start considering that 320 ( h. pixel ) x 15KHz ( h. sync ) = 4.8MHz
as dclk is integer you can start selecting the next higher integer...
Card at home :)
i compiled uboot, kernel and a debian base system ..
If i use your parameters in boot.bin here is the serial output :
... SNIP ....
[ 5.082188] [DISP] *** lcd_vbp: 1
<4>[DISP] *** lcd_hspw: 128
[ 5.088901] [DISP] *** lcd_hspw: 128
<4>[DISP] *** lcd_vspw: 4
[ 5.095181] [DISP] *** lcd_vspw: 4
<4>[DISP] *** lcd_frame_frq: 66Hz
[ 5.101897] [DISP] *** lcd_frame_frq: 66Hz
<4>[DISP] ***
[ 5.107396] [DISP] ***
<4>[DISP] *** Err01: Violate "lcd_hbp > lcd_hspw"
[ 5.114180] [DISP] *** Err01: Violate "lcd_hbp > lcd_hspw"
<4>[DISP] *** Err02: Violate "lcd_vbp > lcd_vspw"
[ 5.124093] [DISP] *** Err02: Violate "lcd_vbp > lcd_vspw"
<4>[DISP] *** Err04: Violate "(lcd_vt/2) >= (lcd_vbp+lcd_y+2)"
[ 5.135140] [DISP] *** Err04: Violate "(lcd_vt/2) >= (lcd_vbp+lcd_y+2)"
<4>[DISP] ***
[ 5.143065] [DISP] ***
<4>[DISP] *** Try new parameters, you can make it pass!
... SNIP ....
Of course, no output with a DIY vga to rgb scart cable (not tested :x)
If i use standard VGA Fex with a standard VGA monitor, all works :)
i'm reading docs for now ^^
EDIT = i've just tested my vga to scart and it works with a xp pro configured to output 15khz so ...
Need to dig ;D
ok, looks like i get a working .fex.
In xorg logs i can see that the fb modeline is ok.
[lcd0_para]
lcd_used = 1
lcd_x = 384
lcd_y = 224
lcd_dclk_freq = 8
lcd_if = 0
lcd_hbp = 96
lcd_ht = 512
lcd_vbp = 26
lcd_vt = 524
lcd_hv_vspw = 20
lcd_hv_hspw = 32
(II) FBTURBO(0): Modeline "current"x0.0 8.00 384 416 448 512 224 236 256 262 -hsync -vsync -csync (15.6 kHz b)
.. With this modeline i get a picture on an x86/radeon debian system but nothing on the Olinuxino ...
Of course, if i modify modeline for a 640x480 it works but in 31khz so it is not a 'i cannot get a picture with vga' but 'i cannot get a picture when i set a modeline at 15khz' ^^
Any idea ?
I hope that the lcdtovga hack will not restrict the use of old crt monitors :x