MaplePad RP2350 - Enhanced Dreamcast Controller

A feature-rich Dreamcast controller emulator built on the Raspberry Pi RP2350 microcontroller with advanced display support, SD card functionality, and conflict-free pin assignments.

🚀 Features

Core Functionality

• Full Dreamcast Controller Emulation - Standard HKT-7700 and Arcade HKT-7300 modes
• Maple Bus Communication - Native Dreamcast protocol support
• VMU Memory Card Emulation - Complete save game functionality
• Multi-Display Support - SSD1306, SSD1309, and SSD1331 OLEDs
• SD Card Integration - VMU save/load with external storage
• RP2350 Optimization - Enhanced performance and memory utilization

Advanced Features

• Automatic Display Detection - Seamless switching between display types
• Font Rendering System - Custom bitmap font with putString/putLetter functions
• Conflict-Free Pin Assignment - Optimized layout eliminates hardware conflicts
• Enhanced Menu System - Configuration and settings interface
• Real-time Status Display - System information and diagnostics

🔧 Hardware Requirements

Microcontroller

• Raspberry Pi RP2350 (recommended) or RP2040
• USB programming capability
• 3.3V/5V power supply

Display Options (Auto-detected)

• SSD1331 - 96x64 Color OLED (SPI)
• SSD1306 - 128x64 Monochrome OLED (I2C)
• SSD1309 - 128x64 Monochrome OLED (I2C)

Storage (Optional)

• SD Card Module - For VMU save/load functionality
• SPI interface compatible

Controls

• Digital Buttons - A, B, X, Y, Start, D-pad (8 directions)
• Analog Inputs - Left/Right triggers, Analog stick (X/Y)
• Arcade Mode - Additional C and Z buttons (HKT-7300)

📌 Pin Assignment (Conflict-Free)

Controller Inputs

Pin	Function	Description
GP0	Button A	Primary action button
GP1	Button B	Secondary action button
GP4	Button X	Tertiary action button
GP5	Button Y	Quaternary action button
GP6	D-pad Up	Directional pad up
GP7	D-pad Down	Directional pad down
GP8	D-pad Left	Directional pad left
GP9	D-pad Right	Directional pad right
GP10	Start	Start/menu button

Dreamcast Communication

Pin	Function	Description
GP11	MAPLE_A	Maple bus data line A
GP12	MAPLE_B	Maple bus data line B

SD Card Interface (SPI0)

Pin	Function	Description
GP16	SD_MISO	SD card data input
GP17	SD_CS	SD card chip select
GP18	SD_SCK	SD card SPI clock
GP19	SD_MOSI	SD card data output

SSD1331 Color Display (SPI1)

Pin	Function	Description
GP14	SCK	SPI clock
GP15	MOSI	SPI data output
GP20	DC	Data/Command select
GP21	RST	Display reset

SSD1306/SSD1309 Monochrome Display (I2C0)

Pin	Function	Description
GP12	SDA	I2C data (shared with Maple when idle)
GP13	SCL	I2C clock

Configuration & Control

Pin	Function	Description
GP22	OLED_PIN	Display type detection
GP23	PAGE_BUTTON	VMU page control

Analog Inputs (ADC)

Pin	Function	Description
GP26	ADC0	Analog stick X-axis
GP27	ADC1	Analog stick Y-axis
GP28	ADC2	Left trigger (L)
GP29	ADC3	Right trigger (R)

Arcade Mode (HKT-7300)

Pin	Function	Description
GP24	Button C	Additional arcade button
GP25	Button Z	Additional arcade button

Power

Pin	Function	Description
5V	Power In	USB or external 5V supply
3V3	Power Out	3.3V for peripherals
GND	Ground	Multiple ground connections

Available for Expansion

Pin	Status	Notes
GP2	Available	Future expansion
GP3	Available	Future expansion
GP13	Available	When not using I2C displays

🛠️ Building the Firmware

Prerequisites

# Install Pico SDK
git clone https://github.com/raspberrypi/pico-sdk.git
export PICO_SDK_PATH=/path/to/pico-sdk

# Install build tools
sudo apt install cmake gcc-arm-none-eabi ninja-build

Build Process

# Clone repository
git clone [repository-url]
cd MaplePad-alter

# Create build directory
mkdir build && cd build

# Configure build
cmake ..

# Build firmware
ninja maplepad

# Output files:
# - maplepad.elf (main executable)
# - maplepad.uf2 (drag-and-drop programming)
# - maplepad.hex (Intel HEX format)
# - maplepad.bin (binary format)

Programming the Device

# Method 1: UF2 (Recommended)
# 1. Hold BOOTSEL button and connect USB
# 2. Copy maplepad.uf2 to USB drive
# 3. Device automatically reboots

# Method 2: picotool
picotool load maplepad.uf2
picotool reboot

⚙️ Configuration

Display Selection

The system automatically detects the connected display type via GP22:

• Low (0V) - SSD1306/SSD1309 monochrome displays
• High (3.3V) - SSD1331 color display

Controller Mode

Set in maple.h:

#define HKT7700 0  // Standard controller (9 buttons)
#define HKT7300 1  // Arcade stick (11 buttons)

SD Card Features

• Automatic Detection - System detects SD card presence
• VMU Save/Load - Save VMU pages to SD card
• Menu Interface - Access via button combinations

🎮 Usage

Basic Operation

1. Connect to Dreamcast via Maple bus
2. Power on - system initializes automatically
3. Display shows status information
4. Controller functions as standard Dreamcast pad

VMU Operations

• Save to SD: Access SD menu, select save option
• Load from SD: Access SD menu, select load option
• Page Management: Use page button to cycle VMU pages

Menu System

• Access configuration menu via button combinations
• Adjust display settings, calibration, and preferences
• View system information and diagnostics

🔍 Troubleshooting

Build Issues

• Missing Functions: Ensure all source files are included
• Pin Conflicts: Verify pin assignments match hardware
• SDK Version: Use compatible Pico SDK version

Hardware Issues

• No Display: Check power and pin connections
• SD Card Errors: Verify SPI connections and card format
• Controller Not Detected: Check Maple bus wiring

Software Issues

• Boot Failures: Check firmware programming
• Display Corruption: Verify display type detection
• Save/Load Errors: Check SD card functionality

📋 File Structure

MaplePad-alter/
├── src/
│   ├── maple.c              # Main controller logic
│   ├── maple.h              # Core definitions
│   ├── display.c            # Display abstraction layer
│   ├── display.h            # Display interface
│   ├── sdcard.c             # SD card implementation
│   ├── sdcard.h             # SD card interface
│   ├── ssd1306.c/h          # SSD1306 driver
│   ├── ssd1309.c/h          # SSD1309 driver
│   ├── ssd1331.c/h          # SSD1331 driver
│   ├── font.c/h             # Font rendering system
│   └── menu.c/h             # Menu system
├── build/                   # Build output
├── CMakeLists.txt          # Build configuration
└── README.md               # This file

🤝 Contributing

Development Guidelines

• Follow existing code style and conventions
• Test thoroughly on hardware before submitting
• Document any new features or pin assignments
• Ensure backward compatibility when possible

Reporting Issues

• Include hardware configuration details
• Provide build environment information
• Describe steps to reproduce problems
• Include relevant log output or error messages

📄 License

This project is licensed under Creative Commons Attribution 4.0 International License.

Share — copy and redistribute the material in any medium or format
Adapt — remix, transform, and build upon the material for any purpose, even commercially
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made

🙏 Acknowledgments

• Charlie Cole - Original Pop'n Music Controller foundation
• Mackie Kannard-Smith (mackieks) - MaplePad development and enhancements
• Raspberry Pi Foundation - RP2040/RP2350 platform and SDK
• Community Contributors - Testing, feedback, and improvements

🔗 Links

• Original MaplePad Repository
• Charlie Cole's Pop'n Music Controller
• Raspberry Pi Pico SDK
• Dreamcast Maple Bus Documentation

---

Built with ❤️ for the Dreamcast community