VERA Module

VERA is the Versatile Embedded Retro Adapter: a self-contained FPGA module for video, audio, and SD-card access. A host controls it through a compact 8-bit parallel register interface. The host architecture, processor, and address-decoding scheme are deliberately left to the system designer.

VERA combines two tile-or-bitmap graphics layers, 128 sprites, a 256-entry RGB444 palette, a 16-voice sound generator, PCM playback, and an SPI controller. The maintained project adds reproducible open-source FPGA builds, dedicated programming tools, a USB bridge, and a desktop test console while keeping compatibility with the original module central to the design.

Start here

• Origins and Continuation introduces the design and the maintained project.

• Hardware Configurations compares the two supported module configurations.

• Connecting a Host explains the bus pins and how to attach VERA to a host.

• Register Reference is the authoritative offset-based programming reference.

• Working with VRAM and Graphics Programming cover memory layout and rendering.

Note

Register numbers in this manual are offsets selected by A0-A4, not CPU memory addresses. Your hardware may expose them through memory-mapped I/O, an isolated I/O space, a microcontroller GPIO bus, or another bridge.

Overview

• Origins and Continuation
  • The original design
  • Project timeline
  • Compatibility
• The VERA Ecosystem
  • FPGA firmware
  • Programmer and command-line tool
  • Arduino Mega bridge
  • VERA Test Console
• Hardware Configurations
  • Full audio-jack board
  • Mini audio-jack board
  • Common architecture

Integration

• Connecting a Host
  • Parallel interface
  • Read and write cycles
  • Memory-mapped or port-mapped
  • Interrupt handling
  • Bring-up sequence
• Register Reference
  • Quick map
  • VRAM pointers and data ports
  • Control register
  • Interrupt enable
  • Interrupt status
  • Display-controller banks
  • Layer registers
  • PCM audio registers
  • SPI registers
• Working with VRAM
  • Address-space layout
  • Setting a pointer
  • Sequential transfers
  • Two-port patterns
  • Alignment and allocation

Programming

• Graphics Programming
  • Composition order
  • Display setup
  • Palette format
  • Layer modes
  • Sprites
  • A dependable first image
• Audio and Storage
  • Programmable sound generator
  • PCM playback
  • SPI controller
• VERA Test Console
  • Install and connect
  • Test progression
  • Troubleshooting
  • Bridge wiring

Project

• Sources and Scope