reSpeaker Flex with XIAO ESP32S3

Overview

The reSpeaker Flex ESP32 version integrates a pre-soldered XIAO ESP32S3 module on the core board, providing built-in Wi-Fi and Bluetooth connectivity for wireless control and edge processing. Powered by the XMOS XVF3800 voice processor, the system maintains the same modular architecture where the microphone array board connects to the core board through a flexible 24-pin FPC cable, allowing flexible placement inside device enclosures. It supports both circular and linear 4-microphone arrays, enabling either 360° omnidirectional capture or directional front-facing pickup. The system can operate through USB (UAC 2.0) or I2S, while the integrated ESP32S3 enables IoT connectivity, local control, and easier integration with embedded applications.

reSpeaker Flex XVF3800 Linear with XIAO ESP32S3	reSpeaker Flex XVF3800 Circular with XIAO ESP32S3
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Features

• Split modular design: Core board and microphone array board are physically separate, connected via FPC ribbon cable for flexible placement in any product chassis

• Choice of microphone configurations: Swap between circular 4-mic array (360° pickup, 44mm spacing) or linear 4-mic array (180° front directivity, 33mm spacing) using the same core board

• XMOS XVF3800 audio processing: Full suite of AEC, AGC, DoA, multi-channel beamforming, VAD, noise suppression, and de-reverberation

• Dual operation modes: USB UAC 2.0 for plug-and-play with PCs and SBCs; I2S mode for direct embedded integration

• Dual USB connectivity: USB-C port and PH2.0 locking port both support UAC 2.0 audio and DFU firmware upgrade

• On-board speaker amplifier: Supports driving 10W 4 Ohms speakers via JST connector, with 3.5mm AUX headphone output

• XIAO ESP32S3 support: Pre-solidered module adds Wi-Fi/Bluetooth, with I2S and I2C buses wired directly to XVF3800 for wireless control and audio forwarding

• Firmware flexibility: Dual USB firmware variants (2-channel and 6-channel), I2S firmware, DFU upgrade via dfu-util, and configuration persistence across power cycles

• Python SDK: Adjustable recording format, volume, algorithm parameters, and channel routing via Python

Main Components

Core Board

Component / Feature	Description
Main Audio Processor	XMOS XVF3800 (firmware v3.2.1), handles all audio DSP including AEC, beamforming, DoA, and noise suppression
Audio Codec	TLV320AIC3104, handles audio conversion and DAC output
FPC Mic Array Interface	24-pin FPC connector with locking latch, supports up to 8-mic arrays with 2 GPIO lines
USB-C Port	UAC 2.0 audio, DFU firmware upgrade, and power
PH2.0 Port	Locking latch connector; provides the same UAC 2.0 audio and DFU support as the USB-C port
3.5 mm AUX Jack	Side-exit headphone output driven from the on-board DAC
Speaker JST Connector	Upright-mount connector that drives speakers up to 10W at 4Ω; solder pad preserved for hard-wired speaker connection
External Power Terminal	Supplies 12V to the whole system and supports 10W speaker loads (P1 priority)
RST Button	Hardware reset for the XVF3800
SafeMode (Boot) Button	Hold during power-on to enter safe mode for firmware recovery
PWR LED	Green power-on indicator
Debug Pad	Reserved pad for XMOS XTAG4 (not soldered at the factory)
XMOS 3800 IO Headers	Exposed pin headers/pads for I2C, I2S, 5V/GND, speaker pins, and remaining XVF3800 IO
Mounting Holes	4 × M3 mounting holes
XIAO ESP32S3	Supports soldering XIAO ESP32S3 when used as the host device
XIAO ESP32S3 GPIO	Remaining GPIO can be used for IO and peripheral expansion

Circular Array Board

Component / Feature	Description
Microphones	4× PDM MEMS microphones with 44 mm spacing arranged in a circular layout
Pickup Pattern	360° omnidirectional audio capture
Interface	FPC connector to the core board
Mounting	3 × M3 mounting holes for enclosure or housing attachment

Linear Array Board

Component / Feature	Description
Microphones	4× PDM MEMS microphones with 33 mm spacing arranged in a linear layout
Pickup Pattern	Front-facing pickup pattern of approximately 180°, with rear sound suppressed
Interface	FPC connector; cable can be routed from the side or rear
Mounting	2 × M3 mounting holes

XIAO ESP32S3 Support

The reSpeaker Flex core board includes a dedicated footprint for soldering a Seeed Studio XIAO ESP32S3 module, enabling Wi-Fi and Bluetooth connectivity on top of the XVF3800's audio processing pipeline. The SKUs including XIAO (-C4-1 and -L4-1) ship with this module pre-populated; the base SKUs (-C4-0 and -L4-0) leave the footprint unpopulated. When the XIAO is fitted, the following connections are wired between it and the XVF3800:

• I2S bus — dual-bus (playback and record) with shared BCLK, MCLK, and LRCLK for audio streaming in both directions
• I2C bus — for reading and writing XVF3800 configuration parameters from the XIAO
• RST line — XIAO can assert a hardware reset on the XVF3800 via a dedicated IO pin
• Remaining XIAO IO — brought out to labelled pin headers/pads for user expansion

Pin Header

24 FPC cable

The FPC mic array interface is a 24-pin, 0.5mm pitch connector with a locking latch, and the 20cm FPC ribbon cable included in the box is keyed to this connector.

Pin	Signal Name	Type	Function Description	Notes
1	MIC_VDD	Power	Microphone power supply	3.3V supply
2	MIC_VDD	Power	Microphone power supply	Dual pin for enhanced power stability
3	GND	GND	Power return ground	Power GND
4	MIC_CLK	Out	Global clock signal	Core signal, 2–4 MHz
5	GND	GND	Clock shielding ground	Dedicated ground for clock
6	MIC_D1	In	Data line 1	CH1 microphone
7	GND	GND	D1 isolation ground
8	MIC_D2	In	Data line 2	CH2 microphone
9	GND	GND	D2 isolation ground
10	MIC_D3	In	Data line 3	CH3 microphone
11	GND	GND	D3 isolation ground
12	MIC_D4	In	Data line 4	CH4 microphone
13	GND	GND	D4 isolation ground
14	MIC_D5	In	Data line 5	CH5 microphone
15	GND	GND	D5 isolation ground
16	MIC_D6	In	Data line 6	CH6 microphone
17	GND	GND	D6 isolation ground
18	MIC_D7	In	Data line 7	CH7 microphone
19	GND	GND	D7 isolation ground
20	MIC_D8	In	Data line 8	CH8 microphone
21	GND	GND	D8 isolation ground
22	GPIO_1	I/O	General-purpose input/output	Expansion function
23	GPIO_2	I/O	General-purpose input/output	Expansion function
24	GND	GND	GPIO shielding ground	Absorbs GPIO noise

Getting Started

Hardware Preparation

• USB Type-c Cable
• Host Computer or Raspberry Pi

Flash the I2S firmware

To use the reSpeaker Flex with XIAO ESP32S3, please make sure the reSpeaker Flex firmware is the I2S version. Check Firmware Flash to flash the latest I2S firmware. Please vist for section

note

Usually, the reSpeaker Flex with the XIAO ESP32S3 comes with factory firmware configured for the I2S version.

Software Preparation

Install Arduino IDE

Download and Install the stable version of Arduino IDE according to your operating system

Download Arduino IDE

Install Arduino-ESP32

To start the installation process using the Boards Manager, follow these steps:

• Install the current upstream Arduino IDE at the 1.8 level or later. The current version is at the arduino.cc website.

• Start Arduino and open the Settings window.

• Enter one of the release links above into Additional Board Manager URLs field. You can add multiple URLs, separating them with commas.

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

• Open Boards Manager from the sidebar, search ESP32 and click INSTALL.

• Restart Arduino IDE.

Supportive Library

note

Please install the Arduino Audio Tools library in order to run the provided examples.

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