Moband Adapter (Dreamcast Modem To Broadband Replacement)

Discussion in 'Sega Dreamcast Development and Research' started by Dreamcast, May 22, 2014.

  1. Basil

    Basil Guest

    Great project! I do play online game on DC and it will be awesome to play more games and i will place preorder for sure.
     
  2. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Well, I got an error 503 with this link... I'm glad if the website is still online though!

    Else great news man!
     
    Last edited: May 25, 2014
  3. spinksy

    spinksy Peppy Member

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    This would be amazing if it were to be mass produced and sold - we could all meet online with our Dreamcasts again lol
     
    Last edited: May 25, 2014
  4. TriMesh

    TriMesh Site Supporter 2013-2017

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    The SAM3X is quite a nice chip - the only thing that's worth noting is that it only has the ethernet MAC on chip, so you need an external PHY. This isn't a showstopper, but it does cause a bit of a hassle if you want to make something that's homebrew friendly, since most of the PHYs are in nasty packages like QFN. I've been looking at the Tiva C series MCUs from TI, and they look nice (although I haven't actually used them for anything yet, so they might be nastier than I think...).

    I have used those WizNet chips, and they are very nice for adding ethernet into existing products because they have the TCP stack on board. They might be a problem if you just wanted to send and receive raw packets, though, since as far as I can renember you can't bypass the built in stack. This also suggests that Parallax decided that the easiest way to implement TCP/IP on the Propeller was to bypass the question altogether and offload it to another chip.
     
  5. l_oliveira

    l_oliveira Officer at Arms

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    Well the point of having the PHY out of the main chipset is that the whole thing doesn't blow into smoke when lightning struck the ethernet port...

    I agree that QFN isn't nice for amateur development but .... You know ... It's scare to think you're risking to blow everything including the dreamcast itself for something so simple as making assembly easier ...
     
  6. TriMesh

    TriMesh Site Supporter 2013-2017

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    I really don't think that's an issue - if you have a large enough spike on the cable that it can jump the magnetics and blow up the PHY then there is a very good chance that it will get into the power nets and blow up the rest of the board anyway. Of course, this is assuming that you grounded the terminations properly and didn't cheap out and attempt to use capacitor coupling - but since a magjack costs about $1 there really isn't any reason not to do that.

    I guess there might be an edge case where a spike has just enough power to get through the magnetics and blow the PHY while leaving everything else undamaged - but in that case the equivalent situation on an MCU with an internal PHY would be for it to blow up the MCU, and leave everything else undamaged.
     
  7. neoblast

    neoblast Robust Member

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    Amazing work mate, keep us updated please :)
     
  8. DarkSynbios

    DarkSynbios Active Member

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    This looks amazing!! Keep the good work my friend!!! :D
     
  9. cybdyn

    cybdyn Embedded developer (MCU & FPGA)

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    Am i right , if i think it's something similar to make clone of BBA?

    what is plan, or what next step? make pcb design with same measurement as DC modem board?

    any picture or block scheme how this device should work.

    1: what interface it uses. as i know G2 bus can work in two mode (at least):
    1- multiplexed addr/data , slow but simple.
    2- PCI-like, fast, but more complex

    2: what is in another side of device : usb port for connection w/ PC, or/and ETHernet?

    3: Options of such device: hi-speed transfer between DC<>PC ? play online game? or?

    4: Launch games by G2 bus, as alternate source for DreamShell?
     
    Last edited: May 29, 2014
  10. PrOfUnD Darkness

    PrOfUnD Darkness Familiar Face

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    Yeah that's something! Really excited about that!
     
  11. BlueCrab

    BlueCrab Member

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    I don't think the point is to make a BBA clone, but rather something that looks and acts like the modem to the hardware, but doesn't need to dial out and that (eventually) connects directly to an ethernet network. The point seems to be in getting online games working, and most Dreamcast games that had any online functionality didn't work with the BBA at all.

    Being that it is emulating the modem, it uses the normal modem bus interface, which would fall into the first of the two you listed there. That all said, the Lan adapter uses the "slow" mode too.

    At the moment, it is USB. Later he wants to explore ethernet.

    There were already hardware devices that could hook hard drives and such up to G2 long before there were ones for G1. Dan Potter (the original KOS author) built one such device (and a BIOS replacement) called navi -- although he never had any interest that I'm aware of in booting any sort of commercial games off the device. It'd pretty much be trivial to do that with such a device at this point. KOS even still contains the code for accessing the navi IDE device (although it is limited to CHS addressing, unlike the g1ata device which supports both LBA modes and CHS). I don't believe the point of this device is to do any sort of commercial game launching over G2, but it'd probably be just as possible as doing so over the BBA or Lan Adapter.
     
  12. japanese_cake

    japanese_cake Spirited Member

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    By launching games over G2 bus, do you mean having a device with any storage connected to the DC on the G2 bus or simply being able to boot games over ethernet? I am asking because in case of the latter, there is already a client/server solution made by Marcus Comstedt. You can go check his git reop here: https://github.com/zeldin/dc-virtcd (binaries can be found on my blog). I tried it, it is nice but there are some limitations regarding the CDDA and other DMA transferts that cannot be solved with a software based solution :/ Anyway, the source code is there and I suggest you have a glance at it.

    Anyways, GDEMU and MOBAND mods make this year really exciting for the dc fans we are :) Thanks you all!
     
  13. darcagn

    darcagn Site Supporter 2013, Site Supporter 2014

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    I noticed the other day that you had mentioned that on your blog, and I had never heard of it, but I built it and tested it. Seems silly that Marcus would write something like that and not tell anyone or share it. It worked well for Sonic Adventure, but I haven't tested other stuff yet. I made a Mac build and post some more info about it here: http://dcemulation.org/phpBB/viewtopic.php?f=72&t=103136
     
    Last edited: May 30, 2014
  14. Teancum

    Teancum Intrepid Member

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    Wow this all sounds pretty exciting. Can't wait to see where this goes.
     
  15. smf

    smf mamedev

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    I'd have thought that if you're going to the trouble of making hardware that has an Ethernet port, then it would make more sense to clone either the Ethernet or broadband adapter. Although something that could pretend to be all three would obviously be the best solution. The only reason for using the modem is that everyone has one so you don't need to build hardware for the dreamcast side, which you're now doing.
     
  16. TriMesh

    TriMesh Site Supporter 2013-2017

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    If you want to play games, then emulating the modem is the best solution - simply because every single network-capable DC game already has support for it. The network adapter only works with it's supplied browser disc, and the BBA is only supported by a handful of titles.
     
  17. -=FamilyGuy=-

    -=FamilyGuy=- Site Supporter 2049

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    Trimesh is right.

    Basically every online DC game supports the modem, while some support the BBA and none the LAN adapter. Also all dc games work well with 56k speed as long as there isn't too much lag, so for playing games emulating the modem is really the best idea.
     
  18. mauler

    mauler Member

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    I agree that it's important to have the most compatibility. There is only one game that must have the BBA to work online and that is the Homebrew port of DOOM, the BBA is needed for four player death match.

    It would be nice if there could be a switch to allow both modes 56K / Broadband so this dvice is future proofed. This way new hombrews could take advantage of a full speed connection, along with mass storage becoming more common on the DC the sky's the limit.
     
  19. TriMesh

    TriMesh Site Supporter 2013-2017

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    That would hugely add to the complexity of the project, though - just on it's own, the BBA is very hard to get right because it consists of a rather specific version of an obsolete Ethernet chip hooked up via a rather minimalist PCI bridge to the G2 bus. This leaves you with a lot of stuff you need to get right if it's going to work. This is a "added feature" that would (IMO) more than double the complexity of the project.
     
  20. anks

    anks Member

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    Probably doable with some logic such as CPLD along side the processor but would require a lot more than just the modem. Maybe a Psoc from cypress would be a good idea but yet again its getting harder just to support doom. Probably easier to alter doom.
     

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