mcp-ppsspp

An MCP server that exposes PPSSPP — the PlayStation Portable emulator — to any MCP-compatible client (Claude Desktop, Claude Code, etc.) via PPSSPP's built-in WebSocket debugger interface.

Read and write PSP memory, drive games with button input, capture screenshots, set CPU breakpoints, inspect MIPS Allegrex registers — all through a clean tool interface. No bridge plugin needed; PPSSPP's debugger is built into the emulator.

How it works

+------------------+    stdio     +------------------+   WebSocket    +------------------+
|   MCP client     |   JSON-RPC   |    mcp-ppsspp    |   JSON-RPC     |     PPSSPP       |
| (Claude / etc.)  | ===========> |     (Node.js)    | =============> |    (debugger)    |
+------------------+              +------------------+                +------------------+

Unlike the mcp-bizhawk / mcp-mgba bridges (which need a Lua plugin loaded into the emulator), PPSSPP ships with its own debugger WebSocket interface — we just speak JSON to it. No plugin to install.

The connection uses subprotocol debugger.ppsspp.org on PPSSPP's debugger port.

Requirements

• PPSSPP (recent version with WebSocket debugger — 1.7+)
• Node.js 18+
• "Allow remote debugger" enabled in PPSSPP

Install

npm install -g mcp-ppsspp

Or npx -y mcp-ppsspp.

Set up PPSSPP's debugger

1. Launch PPSSPP, load any PSP ISO/EBOOT
2. Settings → Tools → Developer Tools → Allow remote debugger (check the box)
3. PPSSPP will show the active host:port (e.g. ws://192.168.1.10:12345/debugger)
4. Note the port number — you'll set it as an environment variable for the MCP server

Register with your MCP client

Claude Code (CLI)

claude mcp add ppsspp --scope user --env PPSSPP_PORT=12345 mcp-ppsspp

Replace 12345 with your actual port. Verify:

claude mcp list
# ppsspp: mcp-ppsspp - ✓ Connected

Claude Desktop

Edit claude_desktop_config.json:

{
  "mcpServers": {
    "ppsspp": {
      "command": "mcp-ppsspp",
      "env": { "PPSSPP_PORT": "12345" }
    }
  }
}

Restart Claude Desktop after editing.

Configuration

| Env var | Default | Purpose | |----------------|---------------|--------------------------------------------------| | PPSSPP_HOST | 127.0.0.1 | WebSocket host to dial | | PPSSPP_PORT | (required) | WebSocket port — see PPSSPP's debugger settings |

Tools

| Tool | Description | |------|-------------| | ppsspp_ping | Verify connectivity (returns version) | | ppsspp_get_info | Title, disc ID, version, run state | | ppsspp_read8 / ppsspp_read16 / ppsspp_read32 | Read u8 / u16-LE / u32-LE from PSP memory | | ppsspp_write8 / ppsspp_write16 / ppsspp_write32 | Write to PSP memory | | ppsspp_read_range | Read up to 64 KiB as a byte array | | ppsspp_write_range | Write byte array to memory | | ppsspp_read_string | Read null-terminated UTF-8 string | | ppsspp_press_buttons | Set persistent PSP button state | | ppsspp_press_button | Press a button for N frames + auto-release | | ppsspp_send_analog | Set analog stick position | | ppsspp_pause / ppsspp_resume | Pause / resume emulation | | ppsspp_step | Step one MIPS instruction | | ppsspp_reset | Soft-reset the loaded game | | ppsspp_screenshot | Capture framebuffer as inline PNG | | ppsspp_get_registers | Read all MIPS Allegrex registers | | ppsspp_breakpoint_add / _remove / _list | CPU execution breakpoints |

PSP memory map (cheat sheet)

| Range | Region | |--------------------------|---------------------------------| | 0x00010000 - 0x00013FFF | Scratchpad (fast 16 KiB SRAM) | | 0x04000000 - 0x041FFFFF | VRAM (2 MiB GE video memory) | | 0x08000000 - 0x087FFFFF | Kernel RAM (8 MiB, low half) | | 0x08800000 - 0x09FFFFFF | User RAM (24 MiB, where most game state lives) | | 0xBC000000+ | Hardware registers |

PSP is little-endian (MIPS Allegrex). Kernel-mode mirrors at 0x88xxxxxx map to the same physical RAM as 0x08xxxxxx.

PSP buttons

cross, circle, triangle, square, up, down, left, right, start, select, ltrigger, rtrigger, home.

Troubleshooting

| Symptom | Cause / Fix | |---|---| | PPSSPP_PORT must be set on startup | Set the env var to the port shown in PPSSPP's Developer Tools dialog | | WebSocket connection failed | PPSSPP isn't running, "Allow remote debugger" isn't checked, or you have the wrong port | | Tool calls hang / time out | Check the PPSSPP UI is responding; the WebSocket request requires PPSSPP's main loop to dispatch | | Invalid address on memory ops | Address is outside the PSP's mapped regions (user RAM is 0x08800000+, not 0x00000000+) | | Screenshot returns no data | No game loaded — boot an ISO/EBOOT first | | Buttons don't seem to do anything | PPSSPP's input has the buttons but they may not "feel" right via remote input if the game polls fast; try ppsspp_press_button with a longer duration |

Limitations

• No savestate API — PPSSPP's WebSocket debugger doesn't expose savestate.save / load. Use PPSSPP's keybinds (F1-F8 for slots) via the UI for now. Could be hacked by using input.buttons.press to trigger the keybind, but not native.
• Frame-advance is instruction-level only (cpu.stepInto). To advance a whole frame, set a breakpoint at the vblank handler and resume.
• Analog stick is shared state — ppsspp_send_analog updates the persistent stick position; not auto-released.

Development

npm install
npm run dev      # tsc --watch — autobuilds on src/ changes

License

MIT