Seed3 Eurorack Dev Kit

A Eurorack Module Platform for the Daisy Seed3

The Seed3 Eurorack Dev Kit is the premier development board for building your next Eurorack module on the Daisy platform. Create powerful effects, stunning sound sources, and complex utilities, all on a single board.

The Dev Kit carries a host of hardware parameters, including 8 potentiometers, jacks for CV, gate, MIDI, and stereo audio I/O, 2 toggle switches, 2 tactile buttons, and a microSD card reader for sample playback, file generation, and data transfer. Mountable in a standard 3U Eurorack case, the Dev Kit integrates straight into your development rig so you can fully realize your next big Eurorack project.

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Contents

• Features
• Specifications
• Getting Started
• Making Your Own Project
• Hardware Reference
• Resources & Support
• Open-Source Hardware
• License

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Features

Category	Details
Format	3U Eurorack, 28HP
Audio	Stereo audio input and output (AC-coupled)
MIDI	3.5mm TRS MIDI In, Out, and Thru
CV & Gate	4 × CV inputs, 2 × gate inputs, 2 × CV outputs
USB	USB-C port connected to the Seed3's external USB peripheral, for USB features in your firmware
Storage	microSD slot for sample playback, file generation, and data transfer
Potentiometers	8 × 10kΩ linear (B-taper)
Buttons	2 × tactile switches
Toggle Switches	2 × toggle switches (1 × ON-OFF-ON, 1 × ON-ON)
LEDs	1 × RGB LED, 1 × single-color LED

Specifications

Parameter	Value
Processor module	Daisy Seed3
Format	3U Eurorack, 28HP
Power	10-pin Eurorack power header (+12V / -12V)
Current draw	Firmware dependent
Reverse polarity protection	Yes
Module depth	PCB acts as front panel, can install in 3U space. 2mm behind rails.
Audio codec / sample rate	TAC5242 / up to 32-bit, 192kHz
Audio input impedance	100kΩ
Audio output impedance	100Ω
Audio level	10Vpp nominal (Eurorack standard), with headroom up to about 20Vpp
CV input range	-5V to +5V
CV output range	0V to +5V
Gate input threshold	+0.4V
MIDI connectors	3 × 3.5mm TRS Type A (In, Out, Thru)

Warning

Check the ribbon cable orientation before powering up. The red stripe marks -12V. Reverse power protection circuit is installed on the board.

Getting Started

Important

This kit has two USB-C ports: one on the Dev Kit board (J7) and one on the Seed3 module itself. Program the template and read its serial output through the Seed3's USB-C port.

1. Install the toolchain

Follow the Daisy C++ Getting Started guide. It installs the toolchain and clones DaisyExamples, which includes libDaisy (hardware library) and DaisySP (DSP library).

2. Update libDaisy

The Eurorack Dev Kit template and board support are newer than the copy of libDaisy included with DaisyExamples. From your DaisyExamples folder, update libDaisy to its latest version, fetch its own dependencies, and rebuild it:

git submodule update --remote libDaisy
git -C libDaisy submodule update --init --recursive
make -C libDaisy

The first line moves libDaisy to its latest version. The second fetches libDaisy's own dependencies, such as the STM32 drivers it needs to compile. The last line rebuilds libDaisy, which is required after any update.

Caution

Running git submodule update --init --recursive or git pull --recurse-submodules from the DaisyExamples folder afterwards resets libDaisy to the older version DaisyExamples was built with. If that happens, run the three commands above again.

3. Build the template

The starting project for this kit is examples/devkits/Eurorack-DevKit-Template. From the libDaisy folder:

cd examples/devkits/Eurorack-DevKit-Template
make

This creates Eurorack-DevKit-Template.bin in the template's build/ folder.

4. Flash the Seed3

1. Connect a USB-C cable from your computer to the USB-C port on the Seed3 module. The Seed3 is powered over USB while you flash, so the module doesn't need to be in a powered case.

2. Hold BOOT, press and release RESET, then release BOOT.

3. From the template folder, run:

   make program-dfu

   Or, in the Daisy Web Programmer, upload the Eurorack-DevKit-Template.bin file from the build/ folder.

5. Power up and try it out

Mount the Dev Kit in a 3U Eurorack case and connect the Eurorack power ribbon to the power header (P1) with the red stripe on -12V. You can leave the Seed3's USB cable connected so you can watch the serial output.

The template:

• Passes audio from the inputs straight to the outputs.
• Cycles the colors of the RGB LED (LED1) and blinks LED2.
• Outputs a slow rising ramp on CV Out 1 and a falling ramp on CV Out 2 (about a 2.5-second period).
• Echoes MIDI notes received on MIDI In to MIDI Out.
• Prints the state of every control over USB serial on the Seed3's USB-C port. Open any serial monitor to see it.

Making Your Own Project

Edits only take effect on the module after you rebuild and reflash, so start your own project from a copy of the template.

1. Copy the Eurorack-DevKit-Template folder into your DaisyExamples folder and rename it, for example DaisyExamples/MyModule.

2. In the copied Makefile:

   • Set TARGET to your project name, for example TARGET = MyModule.
   • Change LIBDAISY_DIR to point to libDaisy from the new location: LIBDAISY_DIR = ../libDaisy.
   • To use DaisySP, uncomment the DaisySP line and set DAISYSP_DIR = ../DaisySP.

3. Write your module in src/main.cpp. Audio is processed in AudioCallback(): inputs are in[0][i] (left) and in[1][i] (right), and outputs are out[0][i] and out[1][i] (see Audio).

4. Rebuild and flash after every change:

   make
   make program-dfu

   Put the Seed3 into BOOT mode (step 4 above) before each make program-dfu.

Tip

The template builds with debugging enabled (DEBUG = 1, OPT = -Og). For release builds, set DEBUG = 0 and OPT = -O3 in the Makefile. If your program grows too large for the Seed3's internal flash, see the Daisy Bootloader guide.

Hardware Reference

The Ref column lists each part's reference designator, as printed on the board's silkscreen.

Pinout

A printable Pinout PDF is also available.

Audio

Jack	Ref	Signal	Audio Callback
Input Left	J_AUDIO_IN_L1	AUDIO_IN_L	in[0][i]
Input Right	J_AUDIO_IN_R1	AUDIO_IN_R	in[1][i]
Output Left	J_AUDIO_OUT_L1	AUDIO_OUT_L	out[0][i]
Output Right	J_AUDIO_OUT_R1	AUDIO_OUT_R	out[1][i]

Note

Input Right is normalled to Input Left. With nothing patched into Input Right, a signal patched into Input Left feeds both channels.

Potentiometers (8-channel multiplexer)

The eight pots are read through a single ADC pin via an 8-channel analog multiplexer (U12). Set the select lines A/B/C to choose a channel, then read POT_MUX.

Signal	Seed3 Pin
POT_MUX (ADC)	D15
MUX_CTRL_A	D24
MUX_CTRL_B	D25
MUX_CTRL_C	D26

Pot	Ref	Mux Channel
Potentiometer 1	VR1	MUX_CH_0
Potentiometer 2	VR2	MUX_CH_1
Potentiometer 3	VR3	MUX_CH_2
Potentiometer 4	VR4	MUX_CH_3
Potentiometer 5	VR5	MUX_CH_4
Potentiometer 6	VR6	MUX_CH_5
Potentiometer 7	VR7	MUX_CH_6
Potentiometer 8	VR8	MUX_CH_7

CV & Gates

Jack	Ref	Signal	Seed3 Pin
CV In 1	J_CV_IN_1	CV_1_ADC	D18
CV In 2	J_CV_IN_2	CV_2_ADC	D17
CV In 3	J_CV_IN_3	CV_3_ADC	D16
CV In 4	J_CV_IN_4	CV_4_ADC	D19
Gate In 1	J_GATE_IN_1	GPIO_GATEIN_1	D10
Gate In 2	J_GATE_IN_2	GPIO_GATEIN_2	D21
CV Out 1	J_CV_OUT_1	DAC_CV_1	D23 (DAC channel 1)
CV Out 2	J_CV_OUT_2	DAC_CV_2	D22 (DAC channel 2)

Switches

Switch	Ref	Signal	Seed3 Pin	Type
Tactile switch 1	SW1	TAC_SW1	D0	Momentary
Tactile switch 2	SW2	TAC_SW2	D20	Momentary
Toggle switch 1	SW3	TOG_2_A / TOG_2_B	D27 / D7	ON-OFF-ON (3-position, two pins)
Toggle switch 2	SW4	TOG_1	D12	ON-ON

LEDs

LED	Ref	Signal	Seed3 Pin
RGB LED — Red	LED1	LED_R	D9
RGB LED — Green	LED1	LED_G	D28
RGB LED — Blue	LED1	LED_B	D8
Single-color LED	LED2	LED_MONO_1	D11

MIDI

Jack	Ref	Signal	Seed3 Pin	Direction
MIDI Out	J_MIDI_OUT1	MIDI_TX	D13	Out
MIDI In	J_MIDI_IN1	MIDI_RX	D14	In
MIDI Thru	J_MIDI_THRU1	MIDI_RX	D14	Mirrors MIDI In

microSD (SDMMC, 4-bit)

Signal	Seed3 Pin
SDMMC_CK	D6
SDMMC_CMD	D5
SDMMC_D0	D4
SDMMC_D1	D3
SDMMC_D2	D2
SDMMC_D3	D1

USB-C

The Dev Kit's USB-C port (J7) connects to the Seed3's external USB peripheral. It is separate from the USB-C port on the Seed3 module, which is used for programming and for the template's serial output. The module is powered from the Eurorack power header (P1), not from USB.

Signal	Seed3 Pin
USB_OTG_HS_N	D29
USB_OTG_HS_P	D30

Resources & Support

• Product Page: Seed3 Eurorack Dev Kit
• Documentation: docs.daisy.audio
• Community Forum: community.daisy.audio
• Discord: Daisy Discord
• Issues: Report bugs or hardware errata via this repository's Issues tab.

Design Files

• Schematic (PDF)
• Bill of Materials (CSV)
• Pinout (PDF)
• KiCad Design Files

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Open-Source Hardware

The Eurorack Dev Kit is open-source hardware, built to the Open Source Hardware Definition published by the Open Source Hardware Association (OSHWA). The schematics, PCB layouts, bill of materials, and KiCad source files are published so that you can study, modify, manufacture, and sell your own designs based on them.

License

Copyright © 2026 Qu-Bit Electronix, Inc. (dba Daisy)

The hardware design files in this repository are licensed under the CERN Open Hardware Licence Version 2 – Permissive (CERN-OHL-P-2.0).

Subject to the terms of that licence, you may:

• Use, study, copy, modify, and distribute these designs and any products made from them.
• Incorporate these designs, in whole or in part, into closed-source and commercial products.

When you redistribute these designs or products made from them, you must:

• Retain all copyright, licence, and other notices contained in the source files.
• Add a notice to any modified source stating that you modified it, with the date and a brief description of the change.
• Ensure that recipients of any product made from these designs have access to the applicable notices.

These designs are provided "as is", without warranty of any kind, express or implied. See LICENSE for the full licence text, including the disclaimer of warranty and limitation of liability.

Firmware and software, including libDaisy and DaisySP, are licensed separately under the terms included in their respective repositories.

SPDX-License-Identifier: CERN-OHL-P-2.0

Trademarks

DAISY® is a trademark of Qu-Bit Electronix, Inc., registered in the United States. CERN-OHL-P-2.0 grants a license to the copyright and related rights in these designs. It does not grant any right or license to use the DAISY name, logos, product names, or other trademarks of Qu-Bit Electronix, Inc.

Products, derivative designs, and related materials made from these designs may not:

• Use the DAISY name or logo, or any confusingly similar name or mark, in a product name, model number, brand, domain name, or marketing material.
• Reproduce the DAISY name or logo on a PCB silkscreen, front panel, enclosure, packaging, or documentation, except where needed to keep the required licence notices.
• State or imply that the product is made, endorsed, sponsored, certified, or supported by Qu-Bit Electronix, Inc.

You may make truthful, factual statements about compatibility or origin, such as "based on the Seed3 Eurorack Dev Kit design" or "compatible with the Daisy Seed3", provided the statement does not suggest affiliation or endorsement. If you redistribute or sell products derived from these designs, remove the DAISY name and logo from the silkscreen and other artwork before manufacture.

For trademark licensing or permission requests, contact Qu-Bit Electronix, Inc. through daisy.audio/pages/support.