XT Sound PI2040Zero

RP2040 Retro Sound

What is?

RP2040 Retro Sound is a project that enables the Raspberry Pi Pico (RP2040) to serve as a COM port passthrough for various FM retro sound chips like the SAA1099, SN76489, YM3812, and YMF262.

Interactive BOM (bill of materials)

Assembled PCB:

Gerbers available via releases, or you can use whole KiCad project from hardware folder

With this setup, you can bring the authentic sound of classic gaming and computing systems to life using original sound chips. Enjoy the nostalgia of retro audio in a modern, convenient package!

Purpose

The goal of this project is to allow enthusiasts to listen to retro sound with real sound chips without needing any other retro hardware.

How to use

To use this project, you will need a modified version of DosBox-X or a Sega Master System/Sega Genesis emulator that can passthrough sound data directly to the chips via a COM port. COM7 hardcoded right now.

The operation protocol is straightforward and consists of two-byte transfers. The first byte is the command byte:

/*
 * 76543210 - command byte
 * ||||||||
 * |||||||+-- chip 0 / chip 1
 * ||||||+--- address or data
 * ||||++---- reserved
 * ++++------ 0x0...0xE chip id:
 *
 *            0x0 - SN76489 (Tandy 3 voice)
 *            0x1 - YM2413 (OPLL)
 *            0x2 - YM3812 (OPL2)
 *            0x3 - SAA1099 (Creative Music System / GameBlaster)
 *            0x4 - YMF262 (OPL3)
 *            0x5 - YM2612, YM2203, YM2608, YM2610, YMF288 (OPN2 and OPN-compatible series)
 *            ...
 *            0xf - all chips reset/initialization
 */

The second byte is the data byte, which is routed directly to the chip.

Requirements

1. PCB (gerbers available via releases, or you can use whole KiCad project from hardware dir)
2. RP2040 mini: The microcontroller that powers the project.
3. Retro Sound Chips: Choose from SN76489, SAA1099, YM2413, YM3812, YMF262, or any OPN2 compatible chip. The YMF262 is recommended for its versatility.
4. Capacitors and Resistors: A few passive components for stable operation.
5. Basic Soldering Skills: Minimal soldering is required to assemble the hardware.

Credits

PCB designs and all hardware stuff are by Sa Gin