Author Topic: connecting a VGA display  (Read 1663 times)

Offline laludelala

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connecting a VGA display
« on: February 07, 2017, 05:30:52 pm »
This topic is also posted in the Operating System / Cubieboard v5 forum
I am not sure, if configuring a VGA display is a hardware or software/OS issue :-(


Hallo!

I set up the Cubietruck Plus to provide some output to a VGA device on the Display Port (connected with an adapter).
I finally succeeded in changing the resolution to 1280x1024, but the timing parameters are apparently wrong, resulting in a corrupt and flickery image.

Are there any tools available, how to get the correct FEX parameters to set up?
Is there an updated FEX parameter description available, which matches the CB5 (the one on https://linux-sunxi.org/Fex_Guide#disp_init_configuration is for CB3 only and refers to a VGA output which does not exist).



I found the monitor parameters, but I do not know how to match them to FEX values.
Not knowing the VGA signal, it is very difficult to get closer to the scope ...

These are the parameters I found:
Code: [Select]
ludwig@notebook:/home/ludwig# gtf 1280 1024 60 -v -x
 1: [H PIXELS RND]             :     1280.000000
 2: [V LINES RND]              :     1024.000000
 3: [V FIELD RATE RQD]         :       60.000000
 4: [TOP MARGIN (LINES)]       :        0.000000
 5: [BOT MARGIN (LINES)]       :        0.000000
 6: [INTERLACE]                :        0.000000
 7: [H PERIOD EST]             :       15.723577
 8: [V SYNC+BP]                :       35.000000
 9: [V BACK PORCH]             :       32.000000
10: [TOTAL V LINES]            :     1060.000000
11: [V FIELD RATE EST]         :       59.998829
12: [H PERIOD]                 :       15.723270
13: [V FIELD RATE]             :       60.000000
14: [V FRAME RATE]             :       60.000000
15: [LEFT MARGIN (PIXELS)]     :        0.000000
16: [RIGHT MARGIN (PIXELS)]    :        0.000000
17: [TOTAL ACTIVE PIXELS]      :     1280.000000
18: [IDEAL DUTY CYCLE]         :       25.283018
19: [H BLANK (PIXELS)]         :      432.000000
20: [TOTAL PIXELS]             :     1712.000000
21: [PIXEL FREQ]               :      108.883202
22: [H FREQ]                   :       63.599998
17: [H SYNC (PIXELS)]          :      136.000000
18: [H FRONT PORCH (PIXELS)]   :       80.000000
36: [V ODD FRONT PORCH(LINES)] :        1.000000

  # 1280x1024 @ 60.00 Hz (GTF) hsync: 63.60 kHz; pclk: 108.88 MHz
  Modeline "1280x1024_60.00"  108.88  1280 1360 1496 1712  1024 1025 1028 1060  -HSync +Vsync

ludwig@notebook:/home/ludwig#

Using the link below, I get the following FEX parameters:
FEX parametervalueunitremark
lcd_ht1712pxdoes not work, keeping 2300
lcd_hbp352px
lcd_hspw136px
lcd_vt1060pxdoes not work, keeping 1125
lcd_vbp35px
lcd_vspw3px


I used some information about converting the parameters from Uboot to FEX in the following link:
http://linux-sunxi.org/LCD