MiST-Fpga with OSSC

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    Hi Folks!

    I’m trying to get the minimig AGA Core on my MiST Fpga working with the OSSC. Unfortunately, my TV (a Panasonic TX-L37EW5 from 2012) won’t work with any of the LX3,4,5-Settings 🙁
    The MiST is configured to disable the Scandoubler, so Output from it’s VGA is shown as RGBS 313p @ 15.79kHz, 50,47Hz, whilst Output from OSSC is set to VMod 288p, LC313, VSM 2

    But I’ve got another problem…. First of all, the OSSC has to be switched on and set to “AV1: RGBS” prior to powering on the MiST. Otherwise, the OSSC won’t get sync. The upper half of the resulting piucture is pulled to the left and flickering, the lower half is rock solid. I can solve this by lowering VSync Threshold below 5.0us until the sync is lost. Adding threshold to 5.07 will regain sync and the upper half of the picture is solid, too.
    The problem: I have to do this every time I power on the devices. Any solution for this?


    The digitizer chip has issues with non-interlace signals using odd-odd field signalling (identified by VSM=2). One solution is to hook the source to AV3 VGA input (doesn’t MiST already output VGA?) which has a bit different sync processing chain and doesn’t inhibit this issue (but has a few other bugs).


    It’s been some time, I got a new TV and got it working in Non-Linedoubled mode with one Caveeat. I have to replug the Source many times before the OSSC would sync. I now wanted to try out the Scandoubled output of Mist FPGA via RGBHV on AV3.
    My problem:
    Non-Scandoubled output is being correctly recognized as 288p

    and via lx4 with H-Active 1920 and V-Active 270

    there’s a stable picture (but unfortunately shifted to the right (I made use of Horizontal Mask to show this).

    The Linedoubled Output on AV3 is unfortunately recognized as 800×600

    I thought this would be 480p/576p, which I would then lx2 to H-Active 1920/V-Active 540 to get 1920×1080, but how???

    There’s no possibilty to set some sort of Linedoubling for 800×600….

    Edit: My pictures (added via ibb.co) aren’t displayed?!?


    Got the Pictures working….hooray!


    It’s kind of surprising those resolutions work I think the Amiga must be the only machine that ever output 800×600 at 50hz. If you went to 800×600 60hz on your old TV it probably would have worked.

    800×600 cannot be linedoubled. If you’re emulating AGA there weren’t many games that took advantage of anything high resolution as AGA was really slow with high res colour modes sadly.


    You misunderstood…. inserting the Pictures into the Reply worked now. The Problem itself persists.
    The MiST doesn’t output 800×600. It linedoubles it’s 288p-Output, which is recognized as 800×600 by OSSC which isn’t correct. The OSSC should indeed recognize the Signal as 480p/576p!


    Is this behaviour (Selecting 800x600 rather than 576p for Linecount=626) a bug? How to proceed? Is there a possibilty to manual switch the output mode to 576p?


    Ok so you’re saying you want to line double with the mister then line double again with OSSC? Why not just output native from Mister and use OSSCs line multiplication?


    Hi Bucko,

    it’s no MiSTer (HDMI onboard), but a MiST (with VGA in 15kHz/31kHz)

    I have to replug the Source many times before the OSSC would sync. I now wanted to try out the Scandoubled output of Mist FPGA via RGBHV on AV3.

    The OSSC cycles through it’s inputmodes (very(!) fast), but it does not sync. I have to replug the Source (AV1) multiple times to get the OSSc to Sync to what is shown in the first picture in https://videogameperfection.com/forums/topic/mist-fpga-with-ossc/#post-35584 .
    This is quite annoying. So I thought, lx2 576p should be the same like lx4 288p, but maybe without this annoying replugging.


    Just to show you what happens, when I connect the non-scandoubled MiST with Minimig AGA Core running:
    Powering on the MiST

    The Sync won’t get stable until I replug the MiST after it’s fully booted. But even then I have to replug it several times until sync is getting established.

    Don’t mind the noise in the background. It’s just the coffee machine 🙂


    Wish I had a solution for you but all I can say is this doesn’t happen on a real Amiga.


    Well, that would be no issue if I could use AV3 for the linedoubled Output to double again into a 1920x1080p-Frame. But the scandoubled Output gets misdetected


    Is there some kind of serial Port on the OSSC to debug this issues in 15KHz-Mode?


    Who could help here? I guess, there’s some simple elseif-Statement on the linecount which decides the mode to choose?!?


    One step taken, the next to follow….
    I re-enabled the Scandoubler on MiST, soldered a VGA->YPbPr-Cable and hooked this up to AV2 of OSSC.
    I now dialed in the following numbers:
    Linemultiplication-Mode for 480p/576p: 2x
    H. Samplerate: 1362
    H.Synclen: 64
    H.Backporch: 243
    H.Active: 960
    V.Synclen: 5
    V.Backporch: 64
    V.Active: 540
    Sampling Phase: 258°

    Picture is stable and uses the whole 16:9 Screen.
    I then wanted to try out the differences when changing Line2x mode from “Generic 4:3” to 320×240 or 256×240(++ 256×240 aspect 8:7)
    The changes seem to have no effect? Is this setting only available for 240p-Sources?

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