PS-FPGA Project

This project is a recreation of the PS1 in digital hardware for FPGA.
It is not fully complete yet and is the work of multiple authors.
It has been demonstrated to play a number of commercially available PS1 games, albeit without any sound or FMV (e.g. intro videos).

Disclaimer: This is clean-room re-implementation done from the following specs and SW emulators:

• https://psx-spx.consoledev.net
• https://github.com/JaCzekanski/Avocado

This core was implemented using only publically available documentation, with no proprietary knowledge of the original's internals.

Cloning

This repo contains submodules.
Make sure to clone them all with the following command;

git clone --recursive https://github.com/PS-FPGA/ps-fpga.git

Targets

The current design targets the Xilinx Artix 7 (100T) FPGA:

• https://store.digilentinc.com/arty-a7-artix-7-fpga-development-board/

The design should be portable to the MiSTer FPGA system, but special care needs to be paid to:

• Memory subsystem - this core requires a 256-bit AXI interface to DDR / SDRAM with sufficient bandwidth.
• RAM mapping - there are a number of inferred RAMs in the design (x_ram.v files).
• Display - DVI is driven directly from the FPGA pins and needs mapping to the video subsystem.

Memory Map

The design has the following memory map;

• Main RAM -> 0x0000_0000 [2MB-16MB]
• BIOS ROM -> 0x01c0_0000 [512KB]
• CDROM FW -> 0x01C8_0000 [64KB]
• Video RAM -> 0x0300_0000 [1MB]
• Game store (CDROM preload images) -> 0x4000000+

The current design requires that all these things are loaded before releasing reset (e.g. using another preload bitstream), but access is also possible to DDR using a UART -> AXI debug unit.

BIOS

This project can make use of the open-source OpenBIOS;

• https://github.com/grumpycoders/pcsx-redux/tree/main/src/mips/openbios

It can also run the retail BIOS dumped from a console you legally own.

CDFW

The CDROM unit is a RISC-V CPU with a SPI SD interface. Games could be loaded via SPI, or can be preloaded into the 'Game store' memory region.

The current CDFW accepts 'psfcd' files, a converter tool is provided here:

• tools/cue2psfcd

Note: You should only play backups of games or content that you legally own. This project is not designed to assist piracy.

A prebuilt version of the cdfw is provided in images/cdfw.bin (and needs to be loaded to 0x01C8_0000 in DDR).
Building the CDFW requires a copy of the RISC-V toolchain (RV32I).

Games

Convert a game CUE/BIN file into a .psfcd and load into DDR @ 0x4000000.

Hardware

• CPU
• GPU
• GTE
• SPU (stub)
• MDEC (stub - produces a white screen)
• DMA
• CDROM (SPI / RAM based 'CDROM')
• Various peripherals (timers, interrupts, serial ports).
• DVI - driving DVI/HDMI directly from the FPGA pins (TMDS)
• Controller - can be hooked up to a standard controller and memory card.

Limitations

• Currently running at 30MHz instead of 33.8MHz (for DVI purposes).
• CDFW needs completion.
• Missing SPU / MDEC (lack of functioning SPU causes issues for a number of games).