ESP32-S31-Korvo-1 V1.1 Multimedia Development Board User Guide
The ESP32-S31-Korvo-1 is a multimedia development board based on the ESP32-S31 chip with the ESP32-S31-WROOM-3 module. It features a dual-microphone array and supports speech recognition as well as near- and far-field wake-up. The board also integrates peripherals such as LCD, camera, and microSD, and supports JPEG-based video streaming. It is well suited for low-cost, low-power smart speakers, audio/video streaming, and human-machine interaction (HMI) graphical UI product development.
ESP32-S31-Korvo-1 V1.1 (with ESP32-S31-WROOM-3 module on board)
Note: The ESP32-S31-Korvo-1 V1.1 main board can be used together with an LCD expansion board.
1. Description of Components
ESP32-S31-Korvo-1 V1.1 main components distribution (click to enlarge)
1.1 Key Component List
The following list describes the key components on the board in a clockwise direction.
| No. | Component | Description |
|---|---|---|
| 1 | USB Type-C Port (Power) | Power input only; no data communication. |
| 2 | USB Type-C Port (UART) | Can power the board, flash firmware to the chip, and communicate with the ESP32-S31 via the onboard USB-to-UART bridge. |
| 3 | USB-to-UART Bridge | Single-chip USB-to-UART bridge supporting up to 3 Mbps. |
| 4 | Power Switch | Slide toward ON to apply 5 V power; slide away from ON to disconnect 5 V power. |
| 5 | USB 2.0 Type-A Port | Connected to the ESP32-S31 USB 2.0 OTG High-Speed interface and supports the USB 2.0 standard. When used for USB communication, ESP32-S31 acts as a USB Host connected to downstream USB devices, providing up to 500 mA output current. |
| 6 | Buck Converter | Buck DC-DC converter for 3.3 V system power. |
| 7 | 5 V Power-on LED | Lights when USB power is connected to the board. |
| 8 | Switch | TPS2051C USB power switch with 500 mA current limit. |
| 9 | Right Speaker Output Port | Right-channel speaker output; can drive a 4 Ω, 3 W speaker. The pin spacing is 2.00 mm (0.08”). |
| 10 | Right Microphone | Onboard right analog microphone routed to the audio codec. |
| 11 | 5 V to 3.3 V LDO | Converts 5 V to 3.3 V for the audio circuitry. |
| 12 | Right Audio PA Chip | NS4150B low-EMI 3 W mono class-D amplifier driving the right speaker from the codec output. |
| 13 | Function Buttons | Four buttons: PLAY, SET, VOL-, and VOL+, connected to ESP32-S31-WROOM-3 for UI control and audio application testing via dedicated APIs. |
| 14 | Audio Codec Chip | ES8389 low-power stereo codec with dual ADC/DAC, low-noise preamp, headphone driver, digital effects, analog mixing, and gain control. Connected to the ESP32-S31 over I2S and I2C for hardware audio processing independent of application software. |
| 15 | Left Audio PA Chip | NS4150B low-EMI 3 W mono class-D amplifier driving the left speaker from the codec output. |
| 16 | Left Microphone | Onboard left analog microphone routed to the audio codec. |
| 17 | Left Speaker Output Port | Left-channel speaker output; can drive a 4 Ω, 3 W speaker. The pin spacing is 2.00 mm (0.08”). |
| 18 | RGB LED | Addressable RGB LED driven by GPIO37. |
| 19 | 3.3 V to 1.8 V LDO (NC) | Converts 3.3 V to 1.8 V for 1.8 V SPI NAND flash. Not populated by default (NC). |
| 20 | SPI NAND Flash (NC) | Quad SPI NAND flash sharing ESP32-S31-WROOM-3 signals with the microSD interface. Not populated by default (NC). |
| 21 | LCD Connector | Connector for an external LCD daughterboard. |
| 22 | ESP32-S31-WROOM-3 | ESP32-S31-WROOM-3 is a general-purpose module supporting 2.4 GHz Wi-Fi 6, Bluetooth 5.4, Bluetooth Classic, and IEEE 802.15.4 (Zigbee 3.0 and Thread 1.4). The module integrates ESP32-S31, 16 MB SPI flash, and 16 MB PSRAM, and uses an onboard PCB antenna. |
| 23 | microSD Card Slot | Supports 4-bit microSD for audio storage and playback. SDIO 3.0 capable. |
| 24 | 3.3 V to 2.8 V LDO | Converts 3.3 V to 2.8 V for the external camera module. |
| 25 | 3.3 V to 1.5 V LDO | Converts 3.3 V to 1.5 V for the external camera module. |
| 26 | Camera Connector | Connector for an external camera module for image transfer. |
| 27 | Reset Button | System reset. |
| 28 | Boot Button | Firmware download: hold Boot, press and release Reset to enter download mode; flash over the serial port. |
1.2 Development Board Accessories
The ESP32-S31-Korvo-1 V1.1 package may include the following optional accessories. The main board and accessories can also be purchased separately. Available accessories include:
- LCD expansion board: ESP32-S3-LCD-EV-Board-SUB3
- OV3660 camera module
2. Power Supply Instructions
To ensure the stable operation of the development board under high multimedia loads, the power system has the following design features:
-
High-power Supply Requirements:
- Both Type-C ports support power supply.
- Important Note: When simultaneously connecting high-power dual speakers (2x 3W) and outputting power via the USB Type-A port, you must ensure that the main USB power cable and adapter can stably provide 5 V and more than 3 A of current.
-
Independent LDO Power Supply for Audio:
- The mainboard is equipped with an independent 5 V to 3.3 V linear voltage regulator (LDO) for audio, physically isolating the power supply of the audio analog circuit from the system digital circuit, minimizing the interference of digital physical noise on audio pickup/playback quality.
3. Pin Assignment Table
The table below lists ESP32-S31-WROOM-3 module pin assignments to onboard functions.
| Peripheral Category | Pin Name/Function | Corresponding Chip GPIO | Hardware Description |
|---|---|---|---|
| Audio I2S Control | I2S_MCLK | GPIO2 | Master clock signal line |
| I2S_SCLK | GPIO3 | Serial clock signal line | |
| I2S_LRCLK | GPIO4 | Frame clock (left/right channel selection) | |
| I2S_DSIN | GPIO5 | Audio input data line (ADC recording) | |
| I2S_SDOUT | GPIO6 | Audio output data line (DAC playback) | |
| Audio I2C Communication | I2C_SDA | GPIO0 | Configuration data line for audio Codec ES8389 |
| I2C_SCL | GPIO1 | Configuration clock line for audio Codec ES8389 | |
| System Interaction & Indication | PA_CTRL | GPIO7 | Enable control pin for left/right channel amplifier chips |
| WS2812_CTRL | GPIO37 | Addressable RGB LED control signal line | |
| ADC BUTTON | GPIO42 | Button detection pin (PLAY/SET/VOL-/VOL+ use resistor voltage divider ADC sampling detection) | |
| Debug Serial Port | U0TXD | GPIO58 | UART0 transmit end (connected to Type-C UART bridge) |
| U0RXD | GPIO59 | UART0 receive end (connected to Type-C UART bridge) | |
| SD Card / NAND Flash | SDIO 4-bit Interface | GPIO20 ~ GPIO25 | Default connected to microSD card slot. To use SPI NAND Flash instead, zero-ohm resistors on the back of the mainboard need to be resoldered. |
4. Start Application Development
Before powering up the board, make sure that it is in good condition with no obvious sign of damage.
Required Hardware
- ESP32-S31-Korvo-1 V1.1
- One or two speakers
- Two USB 2.0 cables (Standard-A to Type-C)
- Computer running Windows, Linux, or macOS
[!NOTE] Be sure to use a good-quality USB cable. Some cables are for charging only and do not provide the needed data lines and will not work for programming the board.
Optional Hardware
- microSD card
Hardware Setup
- Connect one or two speakers to the speaker output port(s).
- Plug in two USB cables from the PC to both USB ports on the board.
- Turn on the power switch.
- The red power LED should light.
5. Automatic Download
There are two ways to put the board into download mode:
Manual download
- Press and hold the onboard Boot button.
- Press and release the Reset button.
- Release the Boot button. The chip enters download mode.
Automatic download
- The onboard USB-to-UART bridge can drive DTR and RTS to control EN (
CHIP_PU) and the boot Strapping pin automatically. - After building the project, click Download in the IDE. The tool resets the chip and starts flashing without manual button presses.
6. Software Development and Board Support
Software Setup
Proceed to ESP-IDF Get Started to set up the development environment and flash an application to your board.
[!NOTE] The board communicates with the host over USB. Most operating systems (Windows, Linux, macOS) include the required drivers, and the board is recognized automatically once connected. If the device is not recognized or the serial port cannot be opened, see Establish Serial Connection with ESP32-S31.
esp_board_manager
Espressif provides the esp_board_manager component for many development boards to simplify initialization of onboard peripherals such as LCD, audio codec, buttons, and LEDs. See the esp_board_manager component in the ESP Component Registry for supported boards.
Other Development Framework Options
In addition to ESP-IDF, this board supports the following frameworks:
- ESP-Brookesia: Human-machine interaction framework for AIoT devices with graphical UI and smart display applications.
- ESP-GMF: Espressif general multimedia framework with audio/video processing components.
- Bluetooth audio: Unified Bluetooth audio APIs supporting Bluetooth Classic and LE Audio.
- ESP Video Components: Camera, video streaming, and video processing components.
- ESP-Matter: Build Matter and Thread devices for low-power and battery-powered scenarios.
7. Contents and Packaging
This development board is available in several models. See the ESP Product Selector, open the Development Board tab, and browse the available models.
- For retail orders, go to Get Samples.
- For wholesale orders, go to Contact Us.
8. Related Documents
Download the following documents from the ESP32-S31-Korvo-1 user guide:
- ESP32-S31-Korvo-1 V1.1 schematic (PDF)
- ESP32-S31-Korvo-1 V1.1 PCB layout (PDF)
- ESP32-S31-Korvo-1 V1.1 dimensions (PDF)
- ESP32-S31-Korvo-1 V1.1 dimensions source file (DXF) - You can view it with Autodesk Viewer online