Seed3 Desktop Dev Kit

A Synth, Sampler, and Effects Platform for the Daisy Seed3

The Seed3 Desktop Dev Kit is the ultimate Daisy-powered prototyping platform for synths, samplers, and effects. Built around the Seed3, it gives you everything you need to design powerful polysynths, sequenced samplers, and rich DSP effects — all on the same hardware.

With essential audio, MIDI, CV, and control components at your fingertips, the Desktop Dev Kit makes it easy to bring your ideas to life. From stereo audio I/O to hands-on knobs and switches, it's packed with the tools you need to shape your next instrument or effect. Add USB-C connectivity, a microSD card slot, and a dedicated headphone amp, and you've got a ready-made studio workbench for turning concepts into commercial products.

Features

Category	Details
Audio	Stereo line-level input and output, with input jack detection
Headphones	3.5mm headphone output with volume control
MIDI	DIN MIDI In, Out, and Thru
CV & Gate	2 × CV inputs, 2 × gate inputs, 2 × CV outputs
USB	USB-C port for power, programming (with the Daisy bootloader), and USB serial
Storage	microSD slot (with card detect) for firmware updates, samples, presets, configuration, and more
Potentiometers	8 × 10kΩ linear (B-taper)
Buttons	16 × tactile switches, each with an LED
Toggle Switches	2 × toggle switches (1 × ON-OFF-ON, 1 × ON-ON)

Specifications

Parameter	Value
Processor module	Daisy Seed3
Power	+5V via the Dev Kit's USB-C port
Current draw	Firmware dependent
Audio codec / sample rate	TAC5242 / up to 32-bit, 192kHz
Input impedance	20kΩ
Output impedance	100Ω
CV input range	-5V to +5V
CV output range	0V to +5V
Gate input threshold	+0.4V
Board dimensions	197mm × 111mm
MIDI connectors	3 × 5-pin DIN (In, Out, Thru)

Getting Started

Important

This kit has two USB-C ports: one on the Dev Kit board (J7, above the Seed3) and one on the Seed3 module itself. The steps below say which one to use. Day-to-day, you power, program, and monitor the Dev Kit through the board'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 Desktop 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/Desktop-DevKit-UI-Template. It reads every input on the Dev Kit, manages the 16 buttons, 8 pots, and LEDs with libDaisy's UI class, and prints input changes over USB serial. From the libDaisy folder:

cd examples/devkits/Desktop-DevKit-UI-Template
make

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

4. Install the Daisy bootloader (one time)

The template runs from the Daisy bootloader, using the variant that accepts new programs over the Dev Kit's USB-C port. You install the bootloader once, through the Seed3's USB-C port:

Connect a USB-C cable from your computer to the USB-C port on the Seed3 module.
Hold BOOT, press and release RESET, then release BOOT.
From the template folder, run:
```
make program-boot
```
Or choose the v6.x (external) bootloader in the Daisy Web Programmer.

You don't need to reinstall the bootloader unless you switch bootloader variants, or want to program an app to the Seed3's internal flash.

5. Flash the template

Move the USB-C cable to the Dev Kit's USB-C port (J7, above the Seed3). This port also powers the board.
Press RESET, then BOOT on the Seed3. The Seed3's USR LED blinks quickly, then pulses slowly, which means it's ready to receive a program.
From the template folder, run:
```
make program-dfu
```
Or, in the Daisy Web Programmer, upload the Desktop-DevKit-UI-Template.bin file from the build/ folder.

6. Try it out

Once flashed, the Seed3's USR LED blinks at a steady rate, and:

Pressing a tactile switch lights its LED.
CV Out 1 and CV Out 2 output a slow ramp and a saw wave.
MIDI notes sent to MIDI In are echoed to MIDI Out.
Audio at the inputs passes straight through to the outputs and the headphone jack.
A serial monitor connected to the Dev Kit's USB-C port shows a message whenever any input changes.

Making Your Own Project

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

Copy the Desktop-DevKit-UI-Template folder into your DaisyExamples folder and rename it, for example DaisyExamples/MyInstrument.
In the copied Makefile:
- Set TARGET to your project name, for example TARGET = MyInstrument.
- 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.
- Keep the APP_TYPE=BOOT_SRAM and BOOT_BIN lines. They make your program run from the bootloader you installed in step 4.
Write your instrument in src/main.cpp, and adjust the button and pot handling in src/main_page.h. 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).
Rebuild and flash after every change, using the Dev Kit's USB-C port:
```
make
make program-dfu
```
Press RESET, then BOOT, 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.

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	J1	`AUDIO_IN_L`	`in[0][i]`
Input Right	J2	`AUDIO_IN_R`	`in[1][i]`
Output Left	J3	`AUDIO_OUT_L`	`out[0][i]`
Output Right	J4	`AUDIO_OUT_R`	`out[1][i]`
Headphones	J5	`AUDIO_OUT_L` / `AUDIO_OUT_R`	`out[0][i]` / `out[1][i]` (mirrors the main outputs)
Headphone volume	RV1	—	Analog volume control, not read by the Seed3

Input Detection

Jack	Ref	Signal	Seed3 Pin
Input Left	J1	`LEFT_DETECT`	D16
Input Right	J2	`RIGHT_DETECT`	D17

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`

Tactile Switches (2 × shift register)

The 16 tactile switches are read through two daisy-chained shift registers (U4, U5).

Signal	Seed3 Pin
`SR_LATCH`	D9
`SR_CLK`	D8
`SR_DATA`	D10

Switches S1–S16 map to TAC_SW1–TAC_SW16, arranged in two rows of eight:


S1	S2	S3	S4	S5	S6	S7	S8
S9	S10	S11	S12	S13	S14	S15	S16

LEDs (I²C LED driver)

The 16 LEDs (LED_1–LED_16, refs D1–D16) sit in the same two rows of eight as the tactile switches, each LED just above its switch (D1 above S1, through D16 above S16), and are driven by a PCA9685 LED driver (U8) over I²C.

Signal	Seed3 Pin
`I2C_SCL`	D11
`I2C_SDA`	D12

Note

LED refs D1–D16 are component reference designators, not Seed3 pins.

Toggle Switches

Switch	Ref	Signal	Seed3 Pin	Type
Toggle switch 1	SW17	`TOG_1`	D19	ON-ON
Toggle switch 2	SW18	`TOG_2_A` / `TOG_2_B`	D28 / D27	ON-OFF-ON (3-position, two pins)

CV & Gates

Jack	Ref	Signal	Seed3 Pin
Gate In 1	J_GATE_IN1	`GATE_IN1`	D0
Gate In 2	J_GATE_IN2	`GATE_IN2`	D18
CV In 1	J_CV_IN_1	`CV_IN_1`	D20
CV In 2	J_CV_IN_2	`CV_IN_2`	D21
CV Out 1	J_CV_OUT_1	`CV_OUT_1`	D23 (DAC channel 1)
CV Out 2	J_CV_OUT_2	`CV_OUT_2`	D22 (DAC channel 2)

MIDI

Jack	Ref	Signal	Seed3 Pin	Direction
MIDI Out	J11	`MIDI_TX`	D13	Out
MIDI In	J10	`MIDI_RX`	D14	In
MIDI Thru	J8	`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
`SDMMC_DETECT`	D7

USB-C

The Dev Kit's USB-C port (J7) powers the board and connects to the Seed3's external USB peripheral. It is separate from the USB-C port on the Seed3 module.

Signal	Seed3 Pin
`USB_OTG_HS_N`	D29
`USB_OTG_HS_P`	D30

Resources & Support

Product Page: Seed3 Desktop 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

Open-Source Hardware

The Desktop 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

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.

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 Desktop 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.

Name		Name	Last commit message	Last commit date
pcb		pcb
.gitignore		.gitignore
LICENSE.txt		LICENSE.txt
README.md		README.md

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Seed3 Desktop Dev Kit

A Synth, Sampler, and Effects Platform for the Daisy Seed3

Contents

Features

Specifications

Getting Started

1. Install the toolchain

2. Update libDaisy

3. Build the template

4. Install the Daisy bootloader (one time)

5. Flash the template

6. Try it out

Making Your Own Project

Hardware Reference

Pinout

Audio

Input Detection

Potentiometers (8-channel multiplexer)

Tactile Switches (2 × shift register)

LEDs (I²C LED driver)

Toggle Switches

CV & Gates

MIDI

microSD (SDMMC, 4-bit)

USB-C

Resources & Support

Design Files

Open-Source Hardware

License

Trademarks

About

Releases

Packages

Contributors

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Repository files navigation

Seed3 Desktop Dev Kit

A Synth, Sampler, and Effects Platform for the Daisy Seed3

Contents

Features

Specifications

Getting Started

1. Install the toolchain

2. Update libDaisy

3. Build the template

4. Install the Daisy bootloader (one time)

5. Flash the template

6. Try it out

Making Your Own Project

Hardware Reference

Pinout

Audio

Input Detection

Potentiometers (8-channel multiplexer)

Tactile Switches (2 × shift register)

LEDs (I²C LED driver)

Toggle Switches

CV & Gates

MIDI

microSD (SDMMC, 4-bit)

USB-C

Resources & Support

Design Files

Open-Source Hardware

License

Trademarks

About

Resources

Stars

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Releases

Packages

Contributors

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