Help with new BBA adapter (cont. from Cluster)

[3yE]

Well, i checked out the PCI IDs and it appears that C and D series are the same, while C+ series are different. So while your logic didn't necessarily work here, the D chip should be the same what sofware conserns. D is a more compactly integrated hardware design. Though i don't think this is all too important, because C is still being sold.

What you see on the board is unfortunately not a ROM chip, and the network chip is not wired up directly to the Dreamcast G2 port, but throgh this chip. It would carry a programing which identifies itself to the G2 and complies with its signals (which is easy) but also emulates a PCI bus on the other side (which is hard). While Sega could easily license some PCI host softcore, i'm not sure i could afford it. Whatever this chip is, it is solid hardware, and there is no way to "download" its internals. To regain software compatibility, we'd have to debug some original software, however i'm not skilled enough to do that. So while not completely impossible, i'd need help.

-edit: thrown out all PLD speculations.

[3yE]

For the first stage, i want to find out how the original system was wired up. It would be very nice if someone could convert the following to eagle format, or just to a set of well-readable images.

http://www.fuzzymuzzle.com/Kiyoshi/I...cext11_pcb.htm

Next thing, we need a nonpci ethernet chip. Or perhaps a microcontroller with an embedded ethernet chip. The ethernet chip, if its alone, its preferable that it could stream in and out the data at 25 mhz (8-bit) or half when 16-bit without waitstates. This would allow to build a controller later which runs with full ethernet speed and doesn't consume much CPU. The microcontroller should be able to be at least 25 MIPS (or the double? i don't know). If nothing that suits is found, we'll see how we do simpler. I'm striving for making it much, much faster and less CPU-hungry than bITmASTER's simple hookup.

If anone sees any examples of attaching an ethernet controller to a microcontroller, please post. If anyone has any more information on the G2 bus, or can make some analysis, please post. i'm particularly interested whether it's possible to signal waitstates when transferring data to Dreamcast.

If we're successful building this, it will likely be manufactured on demand through the help of DreamcastScene.com.

[ßüboni¢ $oñic]

any update

[3yE]

Have no time to do anything right now. In 2 weeks, i will resume the development. I'm still about to read the PCI specs to see how realistic recreation of the original BBA is - that is, use the same original network chip and emulate only the bridge in hardware, say, with an FPGA.

If that's discarded, we'll see whether emulation of the original BBA using a separate microprocessor could be done. I think we would take Asix AX88796 network adapter or similar, and Atmel FPSLIC for the bridge and emulator. AX1100x LAN System-on-chip is also being evaluated for that matter.

If that all fails, we're just wiring up an AX88796 to something like Lattice Mach-XO or some other CPLD and SRAM and see what we can do. SRAM is to buffer the transfers between the G2 and the LAN chip, so that we can transfer a batch per interrupt call and not just a single byte or word as in prior solutions. This should give us something that is homebrew-only but at least quite fast, much faster than bITmASTERs design and HIT-0300.

If anyone can suggest any other hardware to use, please do so. Do some googling, etc, don't put all of the burden onto me, i've got life as well you know, i'm a total newbee to the task, and i'm not going to earn any money on it, but i have to spend my own money on the development hardware. Any help will increase the probability that this thing actually gets done someday. If someone is located in europe and would like to help building the first prototypes, please contact me.

$oñic, if you'd like to help, why don't you convert the PCB file linked in the last post to some colorful, easy to read images? I'm just very busy with other stuff at the moment, so i'd appreciate that.

[Tomlo]

I wish I knew what you people were talking about.

[quzar]

I do, and it's mostly gibberish.

[3yE]

Urgh, yeah, thanks guzar, how f***ing friendly of you!

[ßüboni¢ $oñic]

$oñic, if you'd like to help, why don't you convert the PCB file linked in the last post to some colorful, easy to read images? I'm just very busy with other stuff at the moment, so i'd appreciate that.

i think ill just send you a money order..

[ßüboni¢ $oñic]

ok i will help anyway possible. what do i need to put that file code n to turn into an image?

)
Layer(8 "unused")
(
Line(470 5165 475 5170 20 30 0x00000020)
Line(470 4780 470 5165 20 30 0x00000020)
Line(2430 2530 2430 2860 20 30 0x00000020)
Line(800 1590 970 1590 20 30 0x00000020)
Line(3745 4970 3745 5360 20 30 0x00000020)
Line(2350 2660 2330 2660 20 30 0x00000020)
)
Layer(9 "silk")
(

[semicolo]

It's the code for a pcb, but I don't know which software was used, maybe pcb under linux.