PROGRAMMABLE SOUND GENERATOR MODULE

SGU-1

REV 1

Nine-channel, four-operator FM synthesis with per-channel filtering, hardware modulation and PCM playback.

A new stereo audio-synthesis device developed for the X65 Microcomputer Project and intended for integration with modern retro computers, original vintage machines and embedded systems.

Contact engineeringEvaluate in SGU-Tracker

Development status: Revision 1 engineering samples. Not for resale.

Gold SGU-1 programmable sound generator module render
SGU-1 REV 1Component-side product render
Channels
9 stereo
Synthesis
4-op FM
Output
48 kHz I²S
Sample memory
64 kB PCM
Package
Castellated module
01

PRODUCT OVERVIEW

Architecture and integration

SGU-1 combines established concepts from OPL/ESFM, OPM, SID, POKEY and Paula in one programmable device: four-operator FM synthesis, flexible operator routing, per-channel subtractive filtering and hardware sweep units.

The module pairs a microcontroller with an audio CODEC. Together they generate a stereo 48 kHz I²S stream, converted by the CODEC to analog stereo line-level output. This provides the synthesis capabilities required by X65 without depending on advanced audio chips that are no longer manufactured.

The same C soft-core implementation runs in the SGU-Tracker and on the castellated hardware module. Host tools and target-side players may be adapted independently; the current C and 6502 players demonstrate two integration paths.

Key features

Synthesis engine

  • Nine channels with four operators per channel
  • Seven waveforms per operator, including sample playback
  • ESFM-style per-operator modulation and output routing
  • Waveform shaping and continuous signed pulse width
  • OPN-style AR / DR / SL / SR / RR envelopes

Modulation and control

  • Per-operator hard sync and ring modulation
  • Selectable LFO waveforms for AM and PM
  • Per-channel volume, frequency and cutoff sweeps
  • Per-channel phase-reset timer
  • Level-driven GATE and one-shot TRIG control

Audio path

  • Per-channel resonant low-pass, band-pass and high-pass filter
  • Stereo 48 kHz I²S output to audio CODEC
  • Analog stereo line-level output
  • 64 kB dedicated PCM sample memory

System integration

  • Castellated module for board-level integration
  • SPI host interface and USB-MIDI playback
  • SGM module format with C and 6502 playback software
  • Targets modern retro, vintage and embedded systems
02

TECHNICAL DATA

Product specifications

Preliminary values for Revision 1 evaluation hardware.

Synthesis
Audio channels 9
FM architecture 4 operators per channel
Operator waveforms 7, including PCM sample
Operator routing Independent output and modulation-input levels
Envelope AR / DR / SL / SR / RR
Channel filter Resonant low-pass, band-pass and high-pass
Modulation Hard sync, ring modulation, AM and PM LFO
Hardware sweeps Volume, frequency and filter cutoff
Audio and memory
Audio output 48 kHz, stereo sound
Signal path I²S to analog stereo line out
PCM sample memory 64 kB
Implementation and host interface
Device type Programmable sound generator module
Implementation Microcontroller and audio CODEC
Host integration Castellated board-edge I/O
Development control SPI, USB-MIDI
Reference playback C and 6502 players for SGM modules
DEVICESTATUS
SGU-1 REV 1Evaluation hardware
NOT FOR RESALE
Availability
Engineering samples
Package
Castellated module
Production data
In preparation
CORESTATUS
SGU-1 C SOFT-CORECanonical implementation
AVAILABLE
Interface
sgu.h
Implementation
sgu.c
Hardware path
VHDL design reference
ENGINEERING & SALES

Need samples or integration information?

Technical and commercial enquiries, orders, quotations and invoicing.

contact@xiaoka.com
03

AUDIO EVALUATION

Listen to SGU-1

Recorded demonstrations of the synthesis engine, played back through the SGU-1 soft-core.

Open the interactive SGU-Tracker
04

DESIGN RESOURCES

Documentation and tools

Current release status for engineering resources.

ResourceDescriptionStatus / action
Product briefArchitecture and system integration overviewIN PREPARATION
Register referenceHost control, synthesis and status register definitionsIN DEVELOPMENT
Gate and trigger behaviorLevel-driven GATE and one-shot TRIG semanticsIN DEVELOPMENT
Hardware design filesModule footprint, pin assignment and reference designPLANNED
SGU-TrackerOnline instrument editor, sequencer and playback environmentOPEN TRACKER
Soft-core sourceShared C implementation used by the tracker and moduleVIEW SOURCE
05

EVALUATION HARDWARE

Revision 1 prototype

Assembled engineering modules and component-side study.

Three assembled SGU-1 prototype boards beside a match for scale
REV 1 prototype batchAssembled modules shown with a match for scale
Black and gold SGU-1 module component-side render
Component-side studyCastellated module form factor