Snes fpc

SuperPico Digital

Digital-to-digital HDMI mod for 2-chip SNES consoles using the Raspberry Pi Pico 2 (RP2350B).

Overview

SuperPico Digital captures native 15-bit digital RGB directly from the S-PPU2's TST pins - bypassing the console's analog video path entirely - and outputs clean HDMI via the RP2350's hardware HSTX peripheral. This approach eliminates the blur inherent in non - 1CHIP SNES consoles and provides a rock-solid, jitter-free image.

Key Features

• Hard Sync Architecture: Uses physical VBLANK and HBLANK wires for perfect frame and line alignment.
• Phase-Locked PIO Loop: A custom PIO program synchronizes to the SNES Pixel Clock (PCLK) phase on every line, completely eliminating horizontal "hot air" jitter.
• Jitter-Free 1:1 Capture: Strategic setup delays ensure the raw SNES data bus is sampled at the peak of stability.
• High Performance: Leverages the RP2350 (Pico 2) HSTX peripheral for 640x480 @ 60Hz HDMI output.

Hardware Requirements

• Console: 2-chip or 3-chip SNES (depending how you count :), e.g., SNS-CPU-GPM-01/02, SHVC-CPU-01.
• NOT compatible with 1-CHIP consoles.
• Microcontroller: Raspberry Pi Pico 2 (RP2350).
• Video Signals: Requires soldering to PPU2 pins for digital RGB, Sync, and Clock.

Wiring Reference

Capture Pins (GP27-GP44 contiguous, PIO1 with GPIOBASE=16)

HDMI Output

Build & Flash

Prerequisites

• Pico SDK
• arm-none-eabi-gcc toolchain
• picotool

Build Commands

# Configure
mkdir build && cd build
cmake .. -DPICO_SDK_PATH=/path/to/pico-sdk

# Compile
make -j8

# Flash
picotool load src/superpico-digital.uf2 -f && picotool reboot

Current Status

• Stable Hardware Sync (HBLANK/VBLANK)
• Jitter-free Pixel Capture
• HDMI Signal Stability (640x480)
• Horizontal Centering and Offset Fixes
• Full 15-bit RGB555 Color (32K LUT with per-channel bit-reversal → RGB565)
• Digital Audio capture
• Master Brightness Logic ($2100) - 6 GPIOs + 74HC4078
• Mode 7 Transparency (/OVER) — 1 GPIO, PPU1 pin 94
• Pixel Blanking (TOUMEI) — 1 GPIO, PPU2 pin 4

Credits & References

• Based on logic from the SNES_TST FPGA project by Opatusos/michael-hirschmugl.
• Inspired by the neopico-hd project for MVS.
• Uses the pico_hdmi library for HSTX output.