Genesis / Megadrive core ported to MiST

[phoboz]

It's a bit tricky to get stable builds now as the fpga is over 95% full. However there was some work done on the sdcard reader that I haven't tried yet. My sdcard became corrupt after heavy usage, so I need to reformat it. Please let me know if anyone has tried the newSD branch from github. Otherwise I will give you an update once I have tried it!

[vebxenon]

It's a bit tricky to get stable builds now as the fpga is over 95% full. However there was some work done on the sdcard reader that I haven't tried yet. My sdcard became corrupt after heavy usage, so I need to reformat it. Please let me know if anyone has tried the newSD branch from github. Otherwise I will give you an update once I have tried it!

Do you have any binary of the new branch?

[Sheldon]

Hello,

any news ?

Best Regards.

[phoboz]

Hello,
There is no bitstream (.rbf) file available for download, I have built the project but not tried it on the MiST yet. I will put the file on the mist-binaries repository once I have make a quick smoke test.

[phoboz]

FPGAGEN Beta (2017-05-18) released

Please find the file:

Code: Select all

fpgagen-beta_20170518.rbf

under:
https://github.com/mist-devel/mist-bina ... es/fpgagen

I have done a quick smoke test, and the games I that usually play are working with sound. The game loading seems to be a bit more stable since the NewSD fix (see above)

Code: Select all

This is a port of fpgagen - Genesis/Megadrive core to additional platform(s)
MiST, Turbo Chameleon 64, Altera/Terasic DE2 board

The core shall be considered a work in progress as there are multiple issues:
1. Sprite flickering on heavy scenes, or on large sprites
2. No LFO modulation of the FM sound
3. Rom file formats supported are .bin and .gen, no support for .smd files
4. The design does not fit on the Altera/Terasic DE1 board anymore

==== Installing the core ====
If you are not buidling the core, copy the following files to the root of your sdcard:
fpgagen.rbf
Config_VGA/FPGAGEN.CFG, or Config_TV/FPGAGEN.CFG (for 15 kHz video)

Then rename the file fpgagen.rbf to core.rbf

[breiztiger]

hi

yes loading game is much strong

thanks for your work

[DanyPPC]

Good Job !
You are on the right way

[vebxenon]

Great! I will update at the evening

[vebxenon]

I've tested the core. OSD is too buggy and gets corrupted soon. But great progress on games , although most racing games have corrupted graphics, like Super Monaco GP.

Keep the good work!

Regards,

Salva

[Sorgelig]

phoboz,

I want to port your core to my MiSTer(MiST ported to a larger FPGA-HPS) system. What branch is better to use?

[phoboz]

Hello Sorgelig,
You should probably use the master branch, as it will be most stable (no experimets before tested)
I have merged in the NewSD branch, which only affects the MiST target.

[Sorgelig]

Hmm.. it look like a lot of redundant things in the core.. ZPU with firmware, SPI for SD...
Not optimized for MiST where you can simply choose required ROM from OSD.

[phoboz]

Yes the osd, rom loading etc. is not utilizing the MiST firmware in full. This port was based on the pc engine core for MiST, which uses a completely different method for loading roms (zpu + firmware on the fpga). This approach occupies a lot of the fpga, so the fpga usage can be decreased if using the MiST method for rom loading on the MiST target. However it was not so easy to find a suitable 16-bit romloader matching the handshake interface of the core. If you are able to use the MiST method for loading roms, osd etc. please share your core. Then it would be possible to resume development on the MiST platform, as it is stalled now due to the fpga beeing almost full.

[bernouilli]

@sorgelig: What is this Mister? I couldn't find anything on it but your repository.

[Sorgelig]

Because MiSTer is my project and currently i'm the only who is working in it.
https://github.com/MiSTer-devel/Main_MiSTer/wiki

btw, i've managed to clean FPGAGen from redundant parts and now it works on MiSTer using very similar to MiST API. Just need some time to polish the port.

[DrOG]

Nice work, looking forward to it!

[NegSol]

@Sorgelig - Really great project - I think you nailed the specs. This could really make some mist fans even more happy! We only need to find a solution to get USB devices attached. But I guess this should not be an issue considering the GPIOs on the board. I am already considering getting a board.

[NegSol]

Okay, I now see the DE10 Nano got an USB OTG port. So all is good

[bernouilli]

It sounds great.
I have questions though :
- why not use SRAM instead of SDRAM? Is it because it's more expensive and not available in high capacity?
- the is no SD card port, where do you store the files?

[Gehstock]

- probably
- https://github.com/MiSTer-devel/Main_Mi ... le-SD-card

[NML32]

I think a new topic should be created for the MiSTer.

[phoboz]

A topic related to both Genesis and MiSTer is that: If there are enough gpio pins? SRAM could be put on one of the daughter boards in addition to SDRAM. If fpgagen were to use SRAM for graphics memory, the bandwidth problem which causes sprite flickering would most likely be gone. Since most 16-bit consoles and arcade boards, such as Capcom CPS use SRAM (or at least pseudo SRAM in the CPS case) such cores would be easier to develop and they would reflect the original hardware more closely.

[Sorgelig]

here is the port of FPGAGen for MiSTer:
https://github.com/MiSTer-devel/FpgaGen_MiSTer
Grab it in current revision since currently it uses very similar to MiST API and SDRAM. I plan to modify the memory module on this core to try to fix graphics problems. MiSTer has enough Block RAM to put Genesis RAM and VRAM there. ROM memory probably can be placed into DDR3.
About MiSTer itself, i will create a separate topic for Q&A.

[Sorgelig]

After i've replaced VRAM with BRAM, large sprite problem has gone!

[Sorgelig]

Another odd problem with this core is 3420/8 = 427,5 pixels in line...
For analog video it's not a problem while scaler IP using digital signal has problem...