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FRANK Genesis

Official page: frank.rh1.tech — hub for all FRANK boards and firmware.

Sega Genesis / Mega Drive emulator for Raspberry Pi Pico 2 (RP2350) with HDMI output, SD card, NES/SNES gamepad, and I2S audio.

Screenshots
Boot screen Gameplay
Strategy game Aladdin

Supported Boards

This firmware is designed for the following RP2350-based boards with integrated HDMI, SD card, and PSRAM:

  • FRANK — A versatile development board based on RP Pico 2, HDMI output, and extensive I/O options.
  • Murmulator — A compact retro-computing platform based on RP Pico 2, designed for emulators and classic games.

Both boards provide all necessary peripherals out of the box (no additional wiring required).

Features

  • Native 320×240 HDMI video output via PIO
  • Full YM2612 FM synthesis and SN76489 PSG sound emulation
  • 8MB QSPI PSRAM support for ROM and emulator state
  • SD card support for ROM files and save states
  • NES and SNES gamepad support (directly connected)
  • USB gamepad support (via native USB Host)
  • Runtime settings menu (CPU/PSRAM frequency, audio, display options)
  • CRT scanline effect for authentic retro look
  • Configurable frameskip for performance tuning

Hardware Requirements

  • Raspberry Pi Pico 2 (RP2350) or compatible board
  • 8MB QSPI PSRAM (mandatory!)
  • HDMI connector (directly connected via resistors, no HDMI encoder needed)
  • SD card module (SPI mode)
  • NES or SNES gamepad (directly connected) — OR —
  • USB gamepad (via native USB port)
  • I2S DAC module (e.g., TDA1387, PCM5102) for audio output

Note: When USB HID is enabled, the native USB port is used for gamepad input. USB serial console (CDC) is disabled in this mode; use UART for debug output.

PSRAM Options

FRANK Genesis requires 8MB PSRAM to run. You can obtain PSRAM-equipped hardware in several ways:

  1. Solder a PSRAM chip on top of the Flash chip on a Pico 2 clone (SOP-8 flash chips are only available on clones, not the original Pico 2)
  2. Build a Nyx 2 — a DIY RP2350 board with integrated PSRAM
  3. Purchase a Pimoroni Pico Plus 2 — a ready-made Pico 2 with 8MB PSRAM

Board Configurations

Two GPIO layouts are supported: M1 and M2. The PSRAM pin is auto-detected based on chip package:

  • RP2350B: GPIO47 (both M1 and M2)
  • RP2350A: GPIO19 (M1) or GPIO8 (M2)

HDMI (via 270Ω resistors)

Signal M1 GPIO M2 GPIO
CLK- 6 12
CLK+ 7 13
D0- 8 14
D0+ 9 15
D1- 10 16
D1+ 11 17
D2- 12 18
D2+ 13 19

SD Card (SPI mode)

Signal M1 GPIO M2 GPIO
CLK 2 6
CMD 3 7
DAT0 4 4
DAT3/CS 5 5

NES/SNES Gamepad (directly connected)

Signal M1 GPIO M2 GPIO
CLK 14 20
LATCH 15 21
DATA 1 16 26
DATA 2 17 27

Note: Gamepad 2 uses the same CLK and LATCH as Gamepad 1, only the DATA pin differs.

I2S Audio

Signal M1 GPIO M2 GPIO
DATA 26 9
BCLK 27 10
LRCLK 28 11

PS/2 Keyboard (directly connected)

Signal M1 GPIO M2 GPIO
CLK 0 2
DATA 1 3

Controller Support

NES Gamepad (3-button mode)

NES Button Genesis Button Notes
D-pad D-pad Direct mapping
A A
B B
A + B C Button combo required
Start Start
Select + Start Settings Opens settings menu

SNES Gamepad (6-button mode)

The emulator automatically detects SNES controllers and provides full 6-button support.

SNES Button Genesis Button Notes
D-pad D-pad Movement
B (bottom) A Jump
A (right) B Primary action
Y (left) C Secondary action
X (top) C Secondary action (alternate)
L (shoulder) A Jump (alternate)
R (shoulder) B Primary action (alternate)
Start Start Pause/Menu
Select + Start Settings Opens settings menu

USB Gamepad

When built with USB HID support, standard USB gamepads are supported with automatic button mapping.

PS/2 Keyboard

PS/2 keyboards are supported for direct gameplay without a gamepad.

Keyboard Key Genesis Button Notes
Arrow keys D-pad Movement
A A
S B
D C
Q X 6-button mode
W Y 6-button mode
E Z 6-button mode
Enter Start
Space Select
Alt Mode 6-button mode toggle
ESC Settings Opens settings menu

USB Keyboard

When built with USB HID support (-DUSB_HID_ENABLED=1), USB keyboards are also supported with the same key mappings as PS/2 keyboards (see table above).

Building

Prerequisites

  1. Install the Raspberry Pi Pico SDK (version 2.0+)
  2. Set environment variable: export PICO_SDK_PATH=/path/to/pico-sdk
  3. Install ARM GCC toolchain

Build Steps

# Clone the repository with submodules
git clone --recursive https://github.com/mmatveev/frank-genesis.git
cd frank-genesis

# Or if already cloned, initialize submodules
git submodule update --init --recursive

# Build for M1 layout with NES/SNES gamepad (default)
mkdir build && cd build
cmake -DBOARD_VARIANT=M1 ..
make -j$(nproc)

# Build for M2 layout
cmake -DBOARD_VARIANT=M2 ..
make -j$(nproc)

# Build with USB gamepad support (instead of NES/SNES)
cmake -DBOARD_VARIANT=M1 -DUSB_HID_ENABLED=1 ..
make -j$(nproc)

Build Options

Option Description
-DBOARD_VARIANT=M1 Use M1 GPIO layout (default)
-DBOARD_VARIANT=M2 Use M2 GPIO layout
-DUSB_HID_ENABLED=1 Enable USB gamepad (disables USB serial)
-DCPU_SPEED=504 CPU overclock in MHz (252, 378, 504)
-DPSRAM_SPEED=166 PSRAM speed in MHz (100, 133, 166)
-DZ80_CORE=OLD Z80 core: OLD (ASM optimized, default) or GPX (Genesis-Plus-GX)
-DM68K_CORE=OLD M68K core: OLD (ASM optimized, default) or GPX (Genesis-Plus-GX)
-DFRAMESKIP_LEVEL=3 Frameskip level: 0-4 (0=60fps, 3=30fps default, 4=20fps)

Or use the build script (builds M1 by default):

./build.sh

Release Builds

To build both M1 and M2 variants at multiple clock speeds:

./release.sh

This creates versioned UF2 files in the release/ directory:

  • frank-genesis_m1_504_166_X_XX.uf2 — M1 layout, 504MHz CPU, 166MHz PSRAM
  • frank-genesis_m2_378_133_X_XX.uf2 — M2 layout, 378MHz CPU, 133MHz PSRAM
  • etc.

Flashing

# With device in BOOTSEL mode:
picotool load build/frank-genesis.uf2

# Or with device running:
picotool load -f build/frank-genesis.uf2

Or use the flash script:

./flash.sh

SD Card Setup

  1. Format an SD card as FAT32
  2. Create a genesis/ directory in the root
  3. Copy ROM files (.bin, .md, .gen) to the genesis/ directory
  4. Save states and settings are stored automatically in genesis/

Settings Menu

Press Select + Start during gameplay to open the settings menu. Available options:

  • CPU Frequency: 378 / 504 MHz
  • PSRAM Frequency: 133 / 166 MHz
  • Z80: Enable/Disable the Z80 sound CPU
  • Audio: Master audio enable/disable
  • FM Sound: Enable/Disable YM2612 FM synthesis
  • Channels: Per-channel audio mute (FM1-6, PSG)
  • CRT Effect: Scanline effect on/off
  • CRT Dim: Scanline brightness (10-90%)
  • Frameskip: None / Low / Medium / High / Extreme
  • Gamepad 2: NES / Keyboard / USB / Disabled

Settings are saved to genesis/settings.ini and persist across reboots.

Gamepad 2 Modes

The Gamepad 2 setting controls how the second player input is handled:

Mode Description
NES (default) Second NES/SNES gamepad controls Player 2, keyboard controls Player 1
Keyboard Keyboard controls Player 2 instead of Player 1
USB USB gamepad controls Player 2, NES/SNES gamepad controls Player 1
Disabled Player 2 input is disabled

Troubleshooting

Device won't boot after changing settings

If you configure settings that prevent the device from booting (e.g., incompatible CPU/PSRAM frequencies), remove the genesis/settings.ini file from the SD card to restore defaults.

License

GNU Affero General Public License v3. See LICENSE for details.

This project is primarily based on Gwenesis by bzhxx.

Additional code or concepts are incorporated from:

Project Author(s) License Used For
Gwenesis bzhxx AGPL v3 Core emulator
pico-megadrive xrip AGPL v3 I2S audio driver
Z80 Emulator Marat Fayzullin Non-commercial Z80 CPU core
Genesis-Plus-GX Charles MacDonald, Eke-Eke Non-commercial Reference, optional CPU cores
ClownMDEmu Clownacy AGPL v3 Reference
ARMZ80 Fredrik Ahlström (FluBBa) Custom Reference for ARM assembly
jgenesis James Groth MIT Reference
yaze-ag Frank D. Cringle, Andreas Gerlich GPL v2 Z80 reference
Raspberry Pi Pico SDK Raspberry Pi Foundation BSD 3-Clause Hardware abstraction

Author

Mikhail Matveev <xtreme@rh1.tech>

Acknowledgments

  • @bzhxx for Gwenesis emulator
  • @xrip and @dncraptor for pico-megadrive and I2S audio driver
  • Marat Fayzullin for the Z80 emulator core
  • Charles MacDonald for the foundational Genesis emulation work
  • Eke-Eke for Genesis-Plus-GX and extensive documentation
  • SEGA for the original Genesis/Mega Drive hardware
  • The Raspberry Pi Foundation for the RP2350 and Pico SDK
  • The Murmulator community for hardware designs and testing

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Sega Genesis emulator for RP2350

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Version 1.02 Latest
Apr 26, 2026
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