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Getting Started with reSpeaker Flex

The reSpeaker Flex is a modular, split-architecture voice processing system built around the XMOS XVF3800 processor, designed specifically for robots and intelligent interaction terminals. Unlike conventional all-in-one mic arrays, the Flex separates the core processing board from the microphone array board the two connected via a flexible FPC ribbon cable allowing the array to be embedded at any physical position within a product enclosure while keeping the processing electronics elsewhere. The system supports two interchangeable microphone array configurations: a circular 4-mic array for omnidirectional 360° capture, and a linear 4-mic array for directional front-facing pickup with rear suppression. Both boards connect to the same core board through a standardized 24-pin FPC interface, and the system operates in either USB (UAC 2.0 plug-and-play) or I2S mode for embedded integration. An optional XIAO ESP32S3 module can be soldered onto the core board for wireless connectivity and expanded control.

Circular mic Series​

reSpeaker Flex XVF3800 reSpeaker Flex XVF3800 Circular with XIAO ESP32S3
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Linear mic Series​

reSpeaker Flex XVF3800 reSpeaker Flex XVF3800 Linear 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 (optional): Solder-on 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 / FeatureDescription
Main Audio ProcessorXMOS XVF3800 (firmware v3.2.1), handles all audio DSP including AEC, beamforming, DoA, and noise suppression
Audio CodecTLV320AIC3104, handles audio conversion and DAC output
FPC Mic Array Interface24-pin FPC connector with locking latch, supports up to 8-mic arrays with 2 GPIO lines
USB-C PortUAC 2.0 audio, DFU firmware upgrade, and power
PH2.0 PortLocking latch connector; provides the same UAC 2.0 audio and DFU support as the USB-C port
3.5 mm AUX JackSide-exit headphone output driven from the on-board DAC
Speaker JST ConnectorUpright-mount connector that drives speakers up to 10W at 4Ω; solder pad preserved for hard-wired speaker connection
External Power TerminalSupplies 12V to the whole system and supports 10W speaker loads (P1 priority)
RST ButtonHardware reset for the XVF3800
SafeMode (Boot) ButtonHold during power-on to enter safe mode for firmware recovery
PWR LEDGreen power-on indicator
Debug PadReserved pad for XMOS XTAG4 (not soldered at the factory)
XMOS 3800 IO HeadersExposed pin headers/pads for I2C, I2S, 5V/GND, speaker pins, and remaining XVF3800 IO
Mounting Holes4 × M3 mounting holes
XIAO ESP32S3Supports soldering XIAO ESP32S3 when used as the host device
XIAO ESP32S3 GPIORemaining GPIO can be used for IO and peripheral expansion

Circular Array Board​

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Component / FeatureDescription
Microphones4× PDM MEMS microphones with 44 mm spacing arranged in a circular layout
Pickup Pattern360° omnidirectional audio capture
InterfaceFPC connector to the core board
Mounting3 × M3 mounting holes for enclosure or housing attachment

Linear Array Board​

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Component / FeatureDescription
Microphones4× PDM MEMS microphones with 33 mm spacing arranged in a linear layout
Pickup PatternFront-facing pickup pattern of approximately 180°, with rear sound suppressed
InterfaceFPC connector; cable can be routed from the side or rear
Mounting2 × M3 mounting holes

XIAO ESP32S3 Support​

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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

An FPC Wi-Fi antenna (for the on-board antenna-free XIAO ESP32S3) is included as an accessory with all XIAO-equipped variants.

Pin Header​

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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.

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PinSignal NameTypeFunction DescriptionNotes
1MIC_VDDPowerMicrophone power supply3.3V supply
2MIC_VDDPowerMicrophone power supplyDual pin for enhanced power stability
3GNDGNDPower return groundPower GND
4MIC_CLKOutGlobal clock signalCore signal, 2–4 MHz
5GNDGNDClock shielding groundDedicated ground for clock
6MIC_D1InData line 1CH1 microphone
7GNDGNDD1 isolation ground
8MIC_D2InData line 2CH2 microphone
9GNDGNDD2 isolation ground
10MIC_D3InData line 3CH3 microphone
11GNDGNDD3 isolation ground
12MIC_D4InData line 4CH4 microphone
13GNDGNDD4 isolation ground
14MIC_D5InData line 5CH5 microphone
15GNDGNDD5 isolation ground
16MIC_D6InData line 6CH6 microphone
17GNDGNDD6 isolation ground
18MIC_D7InData line 7CH7 microphone
19GNDGNDD7 isolation ground
20MIC_D8InData line 8CH8 microphone
21GNDGNDD8 isolation ground
22GPIO_1I/OGeneral-purpose input/outputExpansion function
23GPIO_2I/OGeneral-purpose input/outputExpansion function
24GNDGNDGPIO shielding groundAbsorbs GPIO noise

Getting Started​

Hardware Preparation​

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

Software Preparation​

Out of Box Usage​

Reset​

The reset (RST) button provides a hardware reset for the reSpeaker Flex when pressed, it restarts the chip and reinitializes the system from the very beginning, just like a full power cycle.

Speaker connection​

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Here you can see how to connect speakers using either the 3.5mm AUX headphone jack or the onboard JST speaker interface, depending on your audio output preference.

Safe Mode​

Safe Mode is a special recovery mode on the reSpeaker Flex that allows you to flash firmware via USB DFU or I2C for devices like the Raspberry Pi and ESP32.

If you've previously flashed the I2S firmware and want to switch back to the USB firmware, you can enter Safe Mode and reflash the USB firmware using USB DFU.

note
  • USB firmware
    • Supports USB DFU only.
    • You can update the device through a USB connection.
    • It does not support I2C DFU.
  • I2S firmware
    • Supports I2C DFU.
    • Allows firmware updates through the I2C interface.
    • It does not support USB DFU.
  • Safe Mode firmware
    • Stored in the Factory partition.
    • Supports both USB DFU and I2C DFU.
    • This is the most flexible recovery firmware.

Use Safe Mode in the following situations

  • Your firmware is not working properly (for example, USB is not detected).
  • You need to re-flash new firmware, but the current firmware is not responding.
  • You accidentally flashed the wrong firmware and want to recover the device.

How to Enter Safe Mode

  • Power off the device completely.
  • Press and hold the Boot button.
  • While holding the Boot button, reconnect the power.
  • The red LED will start blinking, confirming that the device has entered Safe Mode. Now the device is running the Safe Mode firmware stored in the Factory partition.

Update firmware​

Three firmware versions are available in the official GitHub repository. You can choose and flash the appropriate firmware depending on your application requirements. For more details and downloads, please refer to the Github Link:

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Please make sure that you will need to download whole repository.

The USB firmware is designed for use with host operating systems such as Windows, Linux, and macOS when communicating through the USB hardware interface. Two firmware variants are available: respeaker_xvf3800_usb_dfu_firmware_v2.0.x.bin, which provides 2-channel audio, and respeaker_xvf3800_usb_dfu_firmware_6chl_v2.0.x.bin, which provides 6-channel audio. Both firmware versions operate at a 16 kHz sampling rate with 32-bit depth.

You can explore these firmware files in this link

FirmwareChannelsNotes
XXXXXXXXXXXXXXXXXXXXXXX

Connect the reSpeaker Flex to your PC via the USB cable. Note that you need to use the XMOS USB-C port(close to RST Button) to flash XMOS’s firmware.

Install DFU Util​

dfu-util is a command line tool for Device Firmware Upgrade via USB.

  • Download dfu-util-0.11-binaries.tar.xz and extract it, e.g., D:\dfu-util-0.11-binaries\win64\
    Download Link

  • Add the path to dfu-util.exe to your system Path variable:
    My Computer > Properties > Advanced > Environment Variables > Path

  • Open Command Prompt (cmd) and verify installation:

dfu-util -V

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  • Connect the reSpeaker Flex and check device detection:
dfu-util -l

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If you get:
Cannot open DFU device 2886:001a ... (LIBUSB_ERROR_NOT_SUPPORTED)
Proceed with the driver installation step below.

  • Install Zadig
    • Open Zadig → Options > List All Devices
    • Select reSpeaker XVF3800 Flex
    • Install WinUSB driver
    • Power-cycle the device
    • Run dfu-util -l again to confirm detection.

Flash Firmware​

Download the complete firmware repository from GitHub here reSpeaker Flex XVF 3800

  • Run the following command to flash the firmware

    • dfu-util -R -e -a 1 -D /path/to/dfu_firmware.bin

  • On Linux, run it with sudo

    • sudo dfu-util -R -e -a 1 -D /path/to/dfu_firmware.bin

Record and playback with USB Firmware​

Setup Audacity (Windows)​

  1. Open Audacity
  2. Go to Audio Setup > Audio Settings

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  1. Set:
    • Host: Windows WASAPI
    • Recording Device: reSpeaker XVF3800 Flex
    • Channels: 2 (Stereo)
    • Sample Rate: 16000 Hz (for both Project and Default Sample Rate)
    • Sample Format: 16-bit

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  1. Click OK
  2. You’re ready — start recording!

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Tech Support & Product Discussion​

Thank you for choosing our products! We are here to provide you with different support to ensure that your experience with our products is as smooth as possible. We offer several communication channels to cater to different preferences and needs.

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