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[nand2mario]

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[somhi]

Wonderful initiative!
I'm @somhi, and I'm passionate about tinkering with FPGAs and found very addictive porting retro cores to them. Started with Altera ones, and just recently I'm introducing myself to Xilinx and Gowin ones.
Right now, I'm starting to learn the differences from Quartus to Gowin IDE.
I'm posting my Gowin projects at https://github.com/somhi/gowin_stuff
After a mandatory blink, the first core I tried to port to the tang nano 20k is Arcade Galaga. Haven't got video yet but the core is running as I have audio and keyboard working. After that I switched to a test board core where at the moment I only have got VGA video, but would try to port and test rest of board features (hdmi video, sdram, i2s audio, ...)
Hope to learn a lot looking at the Nestang core as an example.

There is a Telegram group https://t.me/tangnano20k also about Tang nano 20k.

[nand2mario]

Feel free to take the hdmi / frame buffer code. It should fit the Galaga.

[somhi]

I'll do. Can you just give a brief technical description on how your framebuffer works? I thought it required more BRAM than the one available in small FPGAs like this.

I've just got VGA video & sound of Arcade Galaga core working. https://t.me/tangnano20k/268

[nand2mario]

The frame buffer is in nes2hdmi.sv. Search for "BRAM frame buffer". It is an 256 x 240 x 6 buffer (45K bytes). Roughly every pixel is upscaled to 3x3 for 720p HDMI.

For the Galaga, suppose your resolution is 288 x 224 16 colors. Then I believe you can use a similar approach with a 288 x 224 x 4 buffer (31.5K bytes). 3x3 upscaling should still work.

[CoreRasurae]

Great project!
Hi, I'm a FPGA fan. I did a couple of projects with FPGAs over the years, mainly Xilinx and Anlogic, now starting with GoWin too. When I find some time I do try to advance my projects, some of them are purely hobby, others would like to take them to the commercial level. With respect to cores I would love to get Next186 working with the Tang Primer 20K, as well as the AO486.
With respect to Nestang I have seen that there are many controllers that are unsupported by the loader. Some controllers are even detected, but have different values for full up, full left, etc... some are coded in 16 bits, others in 8 bits, which makes the loader unable to decode them. Other have different codes for the movement keys. I believe that it should be created, and I might attempt this, a controller object that could override the codes interpretations based on the VID and PID of the USB controller.
Other than that I would also like to keep a port alive for the Tang Primer 20K. BTW you guys did a wonderful work with the DDR3 memory controller.

[nand2mario]

Glad you like the project. The loader's controller support could be improved. If you have any patches or examples, please kindly share them. Thanks.