[rescue] LCD hi res 17" monitor wanted

Sandwich Maker adh at an.bradford.ma.us
Tue Mar 12 07:37:46 CDT 2019

" From: Romain Dolbeau <romain at dolbeau.org>
" Le mar. 12 mars 2019 C  04:41, Sandwich Maker <adh at an.bradford.ma.us> a C)crit
" :
" > i was just playing with your line above and the numbers as explained in
" > the fbfaq, and
" > : uxga " 135000000,73811,60,20,189,20,1600,6,6,18,1200,COLOR,0OFFSET"
" > ;
" > should work, unless i've added something wrong.  anyone in a position
" > to check?
" The bandwidth seems low (and you're missing the 1600 between the 20 and the
" 6).

d'oh!!!  fixed.

i got it by:
adding all the line dots and dividing into the dotclk to get hfreq
then adding all the lines and dividing into hfreq to get vfreq
and playing with sync bits until i got a 60hz frame.

" At 60 Hz, VESA requires 162 MHz
" (<https://www.mythtv.org/wiki/Modeline_Database#VESA_ModePool>)
" (which becomes
" "162000000,75000,60,64,192,304,1600,1,3,46,1200,COLOR,0OFFSET"),

that has much larger hsync width values, and since those dots are
added every line they add a lot to the dot clock.  i would not be
surprised if a crt needed the flyback times.

" I'm on the 75 Hz mode so a 202.5 MHz clock:
" "202500000,93750,75,64,192,304,1600,1,3,46,1200,COLOR,0OFFSET"
" Your low-freq solution might work, it depends on the display itself.

i was assuming an lcd would be fine with a comparatively narrower hsync.

" You can also extract the EDID value from the display in Linux to
" get the 'proper' values (which may or may not work in practice).

hmmm...  it would be a starting point, at least.
something to file away.

" > i observe that calculated decimals can apparently be rounded to
" > integers - hfreq and vfreq come out to 73810.825587752872 and
" > 60.008943089431, and in your line they were 61058.344640434196
" > and 55.007517694085.  am i missing something?
" No, seems to work fine that way...
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh at an.bradford.ma.us                       and think what none thought

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