Product Highlights
- Multi-protocol wireless connectivity: Wi-Fi 6, Bluetooth 5.4 (LE + BR/EDR), and IEEE 802.15.4 (Zigbee / Thread / Matter).
- Gigabit Ethernet: RJ45 interface supporting 10/100/1000 Mbps auto-negotiation.
- USB 2.0 High-Speed Host Interface: The Type-A interface connects to USB 2.0 OTG High-Speed. When the ESP32-S31 operates as a USB Host, it can provide up to 500 mA of external current.
- Onboard audio path: Microphone, ES8311 codec, NS4150B power amplifier, and speaker output port enable direct evaluation of AI voice interaction.
- All GPIOs exposed: Most module pins are routed to the 40-pin header J2, making it easy to connect external sensors and modules.
- Three interfaces for flexible development: USB Serial/JTAG interface and USB-to-UART interface support power supply, firmware flashing, communication, and debugging.
- Built-in current measurement interface: An ammeter can be connected directly in series through the J5 header to measure module power consumption.
Target Users and Application Areas
The official positioning of the board is “for connected AIoT prototyping and validation.” Based on its onboard resources, typical evaluation and development applications include:
- AI voice interaction evaluation: The board integrates a microphone, audio codec, and power amplifier.
- IoT gateway prototyping: Gigabit Ethernet + Wi-Fi 6 + 802.15.4.
- Matter / Thread device development: Can be combined with ESP-Matter to build devices for low-power and battery-powered applications.
- Bluetooth audio and Bluetooth Low Energy applications: Can be used with ESP-BLE-MESH, ESP-BLE-AUDIO, and ESP-GMF.
- USB host peripheral expansion: Peripherals can be connected through the Type-A interface.
- Education, maker projects, and rapid prototyping.
Hardware Configuration Overview
| Item | Description |
|---|---|
| Model | ESP32-S31-Function-CoreBoard-1 (no historical hardware versions) |
| Module | ESP32-S31-WROOM-3, integrating the ESP32-S31 chip |
| Wireless Connectivity | Wi-Fi 6, Bluetooth 5.4 (LE + BR/EDR), IEEE 802.15.4 (Zigbee / Thread / Matter) |
| Wired Networking | RJ45 Gigabit Ethernet, supporting 10/100/1000 Mbps auto-negotiation; the PHY chip connects to the ESP32-S31 through the RGMII interface |
| USB Type-A | USB 2.0 OTG High-Speed; when the ESP32-S31 operates as a USB Host, it can provide up to 500 mA |
| USB Serial/JTAG | USB Type-C, USB 2.0 Full-Speed, supporting power supply, firmware flashing, communication, and JTAG debugging |
| USB-to-UART | USB Type-C, with an onboard USB-to-UART bridge; supports power supply, firmware flashing, and serial communication |
| Audio Codec | ES8311, low-power mono codec featuring a single-channel ADC / DAC, low-noise preamplifier, and headphone driver; connected via I2S and I2C |
| Audio Power Amplifier | NS4150B, low-EMI, 3 W mono Class-D power amplifier |
| Speaker Output | Can drive a 4 Ω, 3 W speaker; pin pitch is 1.25 mm |
| Microphone | Onboard microphone connected to the audio codec chip |
| Buttons and Indicators | Reset button, Boot button, 3.3 V power indicator, addressable RGB LED (GPIO60) |
| Expansion Interface | 40-pin header J2 |
| Current Measurement | J5 header (jumper installed by default from the factory) |
| Power Supply | 5 V to 3.3 V DC/DC converter; TPS2051C USB power switch with a 500 mA output current limit |
Main Components of the Development Board
| No. | Component | Function |
|---|---|---|
| 1 | J2 Header | Exposes all available GPIOs for easy connection to external devices |
| 2 | RJ45 Ethernet Interface | Supports 10/100/1000 Mbps auto-negotiation |
| 3 | Ethernet Transformer | Used for the RJ45 interface |
| 4 | USB 2.0 Type-A Interface | USB Host, up to 500 mA |
| 5 | USB Serial/JTAG Interface | Power supply, firmware flashing, USB communication, and JTAG debugging |
| 6 | USB Type-C-to-UART Interface | Power supply, firmware flashing, and serial communication |
| 7 | 3.3 V Power Indicator | Lights up when USB power is connected |
| 8 | J5 | Module current measurement |
| 9 | 5 V-to-3.3 V DC/DC Converter | Regulated power supply |
| 10 | ESP32-S31-WROOM-3 Module | Main controller and wireless functionality |
| 11 | Microphone | Connected to the audio codec chip |
| 12 | RGB LED | Addressable RGB LED driven by GPIO60 |
| 13 | ES8311 Audio Codec Chip | Hardware audio processing independent of application software |
| 14 | Reset Button | Resets the ESP32-S31 |
| 15 | Speaker Output Port | For a 4 Ω, 3 W speaker |
| 16 | Boot Button | Hold down the Boot button and press Reset once to enter firmware download mode |
| 17 | NS4150B Audio Power Amplifier | Drives the speaker |
| 18 | Ethernet PHY Chip | Connects RGMII to RJ45 |
| 19 | USB-to-UART Bridge | Works with the USB Type-C-to-UART interface |
| 20 | TPS2051C Power Switch | USB power switch with a 500 mA current limit |
Power Supply and Current Measurement
Power Supply Methods (Choose One)
- Power the board through the USB-to-UART interface or the ESP32-S31 USB interface (either one or both can be powered simultaneously). This is the default recommended method.
- Supply power through the 5 V and GND header pins.
Measuring Module Current
- Remove the J5 jumper: The power supply to the onboard peripherals is disconnected from the module. Connect an ammeter in series through the J5 header to measure the module current.
- Install the J5 jumper (factory default): The development board returns to normal operation.
J2 Header Pin Definitions
All available GPIOs are exposed through the 40-pin J2 header. For complete pin descriptions, refer to the official schematic.
| Category | Pins |
|---|---|
| Ground (G) | 1, 2, 8, 33, 34, 37, 38 |
| 3.3 V Power | 35, 36 |
| 5 V Power | 39, 40 |
| UART0 | TX0 (GPIO58), RXD (GPIO59) |
| BOOT / RGB LED | GPIO61 (BOOT), GPIO60 (drives the RGB LED) |
| SDIO | DATA0 (GPIO20), DATA1 (GPIO21), DATA2 (GPIO22), DATA3 (GPIO23), CLK (GPIO24), CMD (GPIO25) |
| General-Purpose GPIOs | GPIO0, 1, 2, 3, 4, 35–49 (refer to the schematic for the actual pin numbers exposed on the header) |
All GPIOs can be configured to a high-impedance state.
Development Support
Development Frameworks
- ESP-IDF: The official primary development framework. Refer to the ESP-IDF Getting Started Guide for ESP32-S31 to set up the development environment and flash firmware.
- Espressif Bluetooth LE Software Ecosystem: ESP-BLE-MESH and ESP-BLE-AUDIO.
- ESP-GMF: Espressif’s General Multimedia Framework, which provides Wi-Fi audio/video examples and unified Bluetooth audio development interfaces for Classic Bluetooth and LE Audio.
- ESP-Matter: Build devices using the Matter and Thread protocols, suitable for low-power and battery-powered applications.
- esp_board_manager: A board-level peripheral management component that simplifies the initialization of onboard peripherals such as LCDs, audio chips, buttons, and LEDs. Check the ESP Component Registry for support information.
Quick Start
Required Hardware: ESP32-S31-Function-CoreBoard-1, USB 2.0 data cable (Type-A to Type-C), and a computer (Windows, Linux, or macOS).
- Check the hardware: Before powering on, make sure the development board is intact and undamaged.
- Connect to the computer: Connect the development board to the computer using a USB data cable. Power can be supplied through either USB Type-C port.
- Set up the environment: Refer to the ESP-IDF Getting Started Guide to configure the development environment.
- Enter download mode: Hold down the Boot button and press the Reset button once, then flash the firmware through UART or the USB Serial/JTAG interface.
- Verify step by step before deployment: Test Wi-Fi, Ethernet, audio, and GPIO functionality individually.
Note: Some USB cables support charging only and cannot transfer data or program the board. If the computer cannot recognize the device, replace the cable and refer to Espressif’s documentation for serial connection and driver installation instructions.
