zx-rgbi-to-vga-hdmi

A converter for ZX Spectrum RGBI video signals to modern VGA and HDMI displays.

For detailed hardware and original software information, see the upstream project:
🔗 ZX_RGBI2VGA-HDMI

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Alternative Firmware Build: Native Pico SDK

If you prefer working directly with the Raspberry Pi Pico SDK and CMake, check out the companion project:
🔗 zx-rgbi-to-vga-hdmi-PICOSDK

This version of the firmware:

• Uses the native Pico SDK instead of the Arduino framework
• Enables more direct control and customization of PIO programs
• Ideal for developers experimenting with low-level video signal processing or custom capture logic

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Features

Software

• Video Output:
  • VGA output with selectable resolutions: 640×480 @60Hz, 800×600 @60Hz, 1024×768 @60Hz, 1280×1024 @60Hz.
  • HDMI (DVI) resolutions: 640×480 @60Hz and 720×576 @50Hz.
  • Optional scanline effect on the VGA output at higher resolutions for a retro look.
  • "NO SIGNAL" message when no input is detected.
• On-Screen Display (OSD) Menu:
  • Full-featured graphical menu system overlaid on video output.
  • Three-button control (UP, DOWN, SEL) for easy navigation.
  • Real-time parameter adjustment with live preview.
  • Tuning mode for video settings without restarting output.
  • Quick VGA/DVI toggle via long SEL press (5 seconds).
  • All settings can be saved to flash memory.
  • Auto-timeout after 10 seconds of inactivity.
  • See OSD Menu Guide for detailed usage instructions.
• Configuration via Serial Terminal:
  • Alternative text-based menu system for headless configuration.
  • Frequency presets for self-synchronizing capture mode (supports ZX Spectrum 48K/128K pixel clocks).
  • Real-time adjustment of all parameters (changes applied immediately).
  • Settings can be saved to flash memory without restart.
• Test/Welcome Screen: Styled after the ZX Spectrum 128K.

Hardware

• Analog to Digital Conversion: Converts analog RGB to digital RGBI.
  • Based on the project:
    🔗 RGBtoHDMI

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Removed Features

• Z80 CLK external clock source. Self-sync capture mode is now preferred.

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Recent Improvements

Performance Improvements

• Video Output Optimization: Streamlined DMA handling for both VGA and DVI/HDMI output modes, resulting in more efficient memory usage and cleaner code structure.
• Buffer Management: Simplified buffer switching mechanisms for improved video processing performance.

Development Experience

• PlatformIO Integration: Full PlatformIO support with Arduino framework for easier development and dependency management.
• Arduino IDE builds: The project can also be built using the Arduino IDE for those who prefer a simpler setup (requires: Optimization -O3, USB Stack - Pico SDK).

Code Quality

• Memory Optimization: Reduced unnecessary memory allocations and pointer complexity in video output modules.
• Architecture Refinements: Better separation of concerns between video input capture and output generation systems.
• Maintainability: Cleaner code structure while preserving critical hardware-specific requirements for reliable video processing.