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Software Support => GroovyMAME => Topic started by: crispux3 on October 18, 2016, 01:02:22 am

Title: Wei-ya M3129 monitor preset and timing chart for VMMAKER
Post by: crispux3 on October 18, 2016, 01:02:22 am

Hi. I know that there is a preset for Wei-ya M3129, but I'm trying to tweak it for my monitor. I found a 29" wei-ya monitor timing chart online, and according to the specs, I believe it is the exact same as (or nearly the same) as my billabs 24.8" BL25C90T monitor that has a wei-ya chassis in it (billabs was an american distributor of wei-ya monitors). Looking at the timing chart that is attached here, how do I go about configuring monitor specs from this information. I know a little bit, but I'm confused on what values I should use for the horizontal and vertical timings. When I've tried to calculate them, I get way different numbers than the m3129 preset. Thanks for your help.



P.S. I'm really trying to understand how timings and calculations work and I also have a Sony PVM 20" monitor, Dell P991 19" crt, and a Philips 20" CRT TV (that for the life of me, I can't get to stop scrolling vertically).

Title: Re: Wei-ya M3129 monitor preset and timing chart for VMMAKER
Post by: machyavel on October 19, 2016, 06:38:44 pm

Here's the way I would calculate, in case it helps...

Let's look at Timings in column "15K".

H:
Display Time: 47.40~50.99us
No Display Time :12.50~16.20us
Bporch: 4.7~8.4us
Sync: 5.0+/-1.52us
Fporch: NDT - Bporch - Sync

V:
Display Time: 220~240 lines
No Display Time: 23~43 lines
Bporch: 16~24 lines
Sync: 2~6 lines
Fporch: NDT - Bporch - Sync

Everything looks variable here so let's choose a starting point.
 
Let's say 320x240@60, since the specs show total line value of 263 then Hfreq = 60x263 = 15780 Hz = 15.78 kHz
so total H time = 1000 * (1/15.78) = 63.37us
If we set Bporch = 5.98us (ok with 4.7~8.4us), Sync = 4.78us (ok with 5.0+/-1.52us), Fporch = 4.78us
then NDT = 15.54us (ok with 12.50~16.20us)
and DT = 48.83us (ok with 47.40~50.99us)

-> (rounded) H timings: 4.8,4.8,6.0

For V timings let's choose Bporch = 16, Sync = 4, Fporch = 3
We need values in ms so:
Bporch = 16/15.78 = 1.014ms
Sync = 0.253ms
Fporch = 0.190ms

-> V timings: 0.190,0.253,1.014