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T-DSP Core

Part of the T-DSP open modular audio platform.

A compact 4-layer digital backplane for the T-DSP modular ecosystem. Hosts a Teensy 4.1 and ESP32 with USB Audio, MIDI, Ethernet, and TDM expansion headers for connecting T-DSP audio modules.

View 3D Render Gallery -- interactive slideshow of all board views

About T-DSP

T-DSP is an open modular audio platform designed for musicians, engineers, and developers who want powerful digital signal processing in a flexible, hackable format. Built around the Teensy microcontroller and the Teensy Audio Library, T-DSP combines studio-quality audio with a growing library of open-source modules.

Learn more at t-dsp.com.

Overview

The T-DSP Core is a 4-layer digital backplane PCB hosting a Teensy 4.1 and ESP32 alongside supporting ICs. It provides USB Audio, MIDI, Ethernet, and TDM expansion headers for connecting T-DSP audio modules -- in a more accessible and cost-effective form factor than the 8-layer Desktop Pro.

Processing

• Teensy 4.1 -- ARM Cortex-M7 running the Teensy Audio Library for real-time DSP (mixing, effects, synthesis, routing). Also receives USB Audio.
• ESP32 -- UI controller, WiFi/Bluetooth. Drives the display, buttons, and encoder, and sends commands to the Teensy over serial.

Connectivity

Audio I/O

• 3.5mm headphone jack -- Switchcraft 35RAPC4BV4
• RCA outputs -- Stereo analog audio output
• S/PDIF -- Digital audio input and output

USB

• USB-C DEVICE -- Power and USB Audio to Teensy with ESD protection
• USB-A HOST -- USB host connector

Networking

• RJ45 Ethernet -- Wired network connectivity

MIDI

• MIDI input -- 3.5mm TRS with optical isolation (H11L1)
• MIDI GPIO -- Configurable for MIDI in, out, or thru

Power

• Dual power input -- USB-C or external supply via JST-XH header, with TPS22860 power switch for automatic switchover
• Reverse polarity protection -- P-channel MOSFET on power inputs
• Power indicators -- LED indicators for 5V and 12V rails

Storage

• SD card -- Accessible via Teensy 4.1 built-in SD slot

Expansion

• 2x TDM expansion headers (2x10 pin, 2.54mm) -- Connect T-DSP audio modules
  • TDM digital audio bus (BCLK, LRCK, DATA_IN, DATA_OUT, MCLK)
  • I2C control bus (SDA, SCL)
  • Power rails (3.3V, 5V, 12V, GND)
  • Control pins (Held-high, Held-low)
• Modules can be soldered directly or socketed with pin headers
• Multiple modules can be chained on the same TDM bus

User Interface

• GPIO header -- Active-low buttons, rotary encoder, and display connections for tactile UI
• OLED display header (128x64, SSD1306) -- Status and menu-driven UI
• 3.2" TFT touchscreen header (ILI9341) -- Touchscreen UI
• SK6812 addressable LED header -- ESP32 and Teensy status indication, plus LED strip control

Board Design

• 4-layer PCB -- F.Cu (components/analog), In1.Cu (ground plane), In2.Cu (signal/digital), B.Cu (components/analog)
• 1.6mm board thickness
• LDO voltage regulation for clean analog power
• Separate analog and digital ground domains
• Buffered digital outputs for reliable module distribution

Project Files

Status

This board is under active development.

If you build one, we'd love to hear how it goes -- please open an issue or reach out with your findings.

Contact

For consulting, custom board design, or commercial licensing inquiries, reach out via LinkedIn.

License

This project is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0).

You are free to share and adapt this work for non-commercial purposes, as long as you give appropriate credit and distribute any derivatives under the same license.