FPGAARCADE minimig compatible board, comments?

[bloodline]

freqmax wrote:
Maybe PS2, but it's a slow I/O and can be outsourced to some dummy pcb with only wires.

It a must since a PS/2 keyboard is the easiest way to get Keyboard control! And who doesn't have (or can't get) a PS/2 mouse?

 And USB hasn't been less complex since last time it was up for discussion :-)

Ok, ok! But it would be nice :-)

[freqmax]

Board space on a board this complex comes at a hefty price. Even a central London apartment would look dirt cheap in comparision..
Thus anything that's specific and slow I/O to a certain "emulation" is preferibly put on a cheaper board that can be reused with future revisions of the main board.

[mikej]

"Are you going to use Hyeprlynx or another Signal Integrity tool to simulate your pcb layout ? When you post the schematics, I will look them over."

Yes, I'll run it through Hyperlynx to see what it looks like, and thanks for the review offer. You can get away with no termination at all for a single memory with very short traces. A couple of designs use a single 50R to VTT per net (spartan3a starter kit). I think I should be ok with just the parallel terminators placed at the end of the net for clock/address/control lines and in the center for the data pins. I will simulate it to be sure.

The dc-dc controllers are from national (lm2852/3) with the recommended inductor from coilcraft. Dedicated VTT linear regulator.

Latency is a problem, thats why I've gone for DDR1 over DDR2. The memory controller can keep four banks open and do 32 bit fully random access on each bank as fast as the Minimig SRAM can. This is useful for some arcade games where I can emulate four ROMS (one per bank) simultaneously.

I've added a header by the (by default) unpopulated joy connectors so you can fit a connector and make a cable to whatever joystick you want. You also have the main expansion connector with lots of IO.

"Thus anything that's specific and slow I/O to a certain "emulation" is preferibly put on a cheaper board that can be reused with future revisions of the main board."

Agreed!

[jkonstan]

Simulate the pcb layout in Hyperlynx, and you will be ok.
The last Spartan3 that I simulated with DDR was only a point to point application, and the only termination resistor required was for DDR_CLK+/-. The rest of the I/O terminations for the interface were tweaked by controlling the Spartan3 pin drivers in the (Xilinx ISE .UCF file). If you use a Spartan3A instead of a Spartan3, you will have to add more external termination resistors because the Spartan3A I/O drivers do not have as much termination/impedance control as the Spartan3 does. Also, there are a lot of good DDR app notes from TI, Freescale, Xilinx etc.. as well.

 :-)

[mikej]

Update:
Thanks for all the comments. The layout has been expanded slightly so it is mini_itx wide and roughly half as deep - so it will fit in a mini-itx case and the two rear fixing holes are in the correct place.

I have decided to go for a twin SPI bus AVR chip for performance reasons and the open source tool chain is better than the PIC. I have ported most of the MiniMig PIC code.

I have added an active filter/buffer for the video out which allows the the daughter board to have a composite/svhs coder.

I'll get an updated layout and schematic up for review as soon as I can.
Regards,
Mike.

[PeterSieg]

Hello mikej.

Thanks for all your work!!

Could you please update us on the actual status of your upcoming fpgaarcade dev board..?

When do you think, a first batch can be made?
In what ball park figure do you expect the total costs?

I am thinking of purchasing a minimig board.. but if your
board will have a lower price tag and will be available wihtin the next couple weeks.. I would rather wait..

Many thanks!
Peter

[FrenchShark]

Hello MikeJ,

It is funny. I am finishing the same kind of board at work :-).
Even if my board will be used as test equipment for multimedia devices, it is "Minimig capable".
The specifications are slightly different:
- Cyclone EP3C16 QFP-240
- 8 MB of 16-bit ZBT SSRAM
- 30-bit VGA
- Stereo audio output
- 2 joystick ports
- PATA 2"5/3"5
- Configuration done with a DLP2232 board (FTDI chip) or a Propeller add-on board.
For the clock I use a 27 Mhz clock along with a MK2712 chip from IDT that can generate a PAL or NTSC clock.

To minimize the traces lengths between the FPGA and the SSRAM, I put the SSRAM "under" the FPGA with no termination resistor. I already have a similar FPGA-SSRAM design running at 66MHz without any trouble.

Regards,

Frederic

[mikej]

Here is an update on the FPGAARCADE board. Layout is complete, routing is going well. I should have some schematics up soon when the pin swapping is complete. It is mini-ITX in width and shrunk a bit vertically. (170mm x 80mm)It has more expansion than you can shake a big stick at.

/MikeJ
WWW.FPGAARCADE.COM

(edit to fix link)

[tonyyeb]

Watching this thread with great interest. Keep up the greak work mikej!

[Darrin]

mikej wrote:
So, everybody happy with using the VGA/DVI/SCART connector on the main card and only having Composite out on the daughter card ??

Living in SCARTless USA, I'd rather have a composite or S-Video out on the card.  :-)

[mikej]

Yes, this has been pointed out. I ran out of IO space.

The daughter board will have comp/s-video out. I may do a tiny little board which plugs into just the small connector in the bottom middle which has just the comp/s-video connector and coder on it. Thats what the extra hole to the right of the connector is for

[Darrin]

mikej wrote:
Yes, this has been pointed out. I ran out of IO space.

The daughter board will have comp/s-video out. I may do a tiny little board which plugs into just the small connector in the bottom middle which has just the comp/s-video connector and coder on it. Thats what the extra hole to the right of the connector is for

That works for me.  :-D

[Crom00]

This is all good news.

Get yourself a good factory and get this sucker made pronto!!!!

I find it amazing how much work is being done by end users compared to the IP onwers of the AtariST and Amiga brands.

[PeterSieg]

Great news! Can't wait to see this getting real!
Do you have already a rough idea on the estimated price tag and some deadline like for example:

Finish layouts - ready for production: Mid June 08
1st batch ready - Mid July 08

Thanks again for your work!

Peter

[mikej]

Hi Peter,

One of the problems is that it is not just board design, there is a lot of other "stuff" to do to make sure it will work. For example, the DDR memory controller is being tested and I have ported most of the PIC code to the AVR.

Layout will be complete by end June and I have enough parts already to build 5 prototypes. These will be sent out to other developers. If all is well then I will kick off a small production run dependent on demand. I aim to get this done by mid August.

The price is going to more than MiniMig certainly, and it is very dependent on the number of boards we make. The board is a lot more flexible and is aimed at people who want to build it into an arcade machine etc as well. It is possible a cost reduced/portable version could happen in the future. The target price is sub $250/Euro160 but this could go up or down (hopefully down).

Cheers,
/Mike

[TheDaddy]

Hi,

Could you post the latest specs please?

Thanks  :-)