Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
ESP32-S3: USB OTG & AI Features Explained (A PCB Engineer’s Deep Dive)
After spending countless hours designing boards around various microcontrollers, I can confidently say that the ESP32-S3 represents one of the most significant leaps forward in the IoT silicon space. Whether you’re building wireless data loggers, camera-based inspection systems, or edge AI devices, this chip deserves serious consideration.
In this guide, I’ll break down the USB OTG and AI capabilities that make the ESP32-S3 stand out from its predecessors—and explain why these features matter for your next project.
What Makes ESP32-S3 Different from Other ESP32 Variants?
Before diving into specific features, let’s establish where the ESP32-S3 fits within Espressif’s lineup. Having worked with nearly every chip in the ESP32 family since 2017, I’ve watched this platform mature substantially.
The ESP32-S3 is a dual-core XTensa LX7 MCU running at 240 MHz with 512 KB of internal SRAM. Unlike the original ESP32’s LX6 cores, the LX7 architecture brings meaningful performance improvements—particularly for signal processing and neural network workloads.
ESP32-S3 Technical Specifications Overview
Specification
ESP32-S3
Original ESP32
ESP32-S2
CPU
Dual-core LX7 @ 240MHz
Dual-core LX6 @ 240MHz
Single-core LX7 @ 240MHz
SRAM
512 KB
520 KB
320 KB
Wi-Fi
802.11 b/g/n
802.11 b/g/n
802.11 b/g/n
Bluetooth
BLE 5.0
Classic + BLE 4.2
None
USB OTG
Yes (Full-speed)
No
Yes
AI Acceleration
Vector Instructions
No
No
GPIO Count
45
34
43
Touch Channels
14
10
14
External PSRAM
Octal SPI Support
Quad SPI
Quad SPI
What immediately stands out is the combination of dual cores, USB OTG support, and AI acceleration. The ESP32-S2 sacrificed the second core and Bluetooth to add USB support. The ESP32-S3 gives you everything.
Understanding USB OTG on the ESP32-S3
USB On-The-Go (OTG) is one of those features that sounds simple but opens up entirely new application possibilities. The ESP32-S3 includes a full-speed USB 2.0 OTG controller with an integrated transceiver.
How USB OTG Works on ESP32-S3
The USB OTG interface allows the ESP32-S3 to function as either a USB device or a USB host—sometimes called “dual-role” operation. The USB data lines connect to fixed GPIO pins 19 (D-) and 20 (D+).
Device Mode: Your ESP32-S3 appears to a computer as a USB device. It can emulate a mouse, keyboard, mass storage device, or virtual COM port (CDC class).
Host Mode: Your ESP32-S3 controls other USB devices. Connect a USB keyboard, flash drive, or camera directly to your embedded system.
ESP32-S3 USB OTG Applications
From my bench testing, here are practical use cases that work reliably:
Application Type
Description
Implementation
Wireless Storage Device
ESP32-S3 hosts USB flash drives and serves files over Wi-Fi
USB Host + SD Card + Web Server
HID Emulation
Act as keyboard/mouse for automation testing
USB Device (TinyUSB stack)
Wi-Fi Network Adapter
Add wireless capability to USB-only devices
USB Device CDC class
LTE MiFi Gateway
ESP32-S3 hosts LTE modem via USB
USB Host + Network stack
Debugging Interface
Program other MCUs wirelessly
USB Host + CMSIS-DAP
The Espressif ESP-IDF framework includes a USB Host Library that handles the complexity of OTG enumeration and device management. The library uses the Synopsys DesignWare Core (DWC2) USB controller—the same IP found in many STM32 microcontrollers.
ESP32-S3 USB OTG Hardware Considerations
When laying out a PCB with USB OTG, keep these points in mind:
The internal PHY eliminates the need for external USB transceivers, reducing BOM cost. However, USB signals are sensitive to impedance mismatches. Keep D+ and D- traces matched, with controlled 90-ohm differential impedance if running longer than an inch or two.
Power delivery matters in host mode. The ESP32-S3 can’t directly supply 500mA to connected devices from its GPIO. You’ll need a power switch IC (like a TPS2041) controlled by a GPIO to manage VBUS power properly.
For dual-role operation, consider using a dedicated development board like the ESP32-S3-USB-OTG from Espressif. This board includes the USB interface switching circuitry, power management, and both Type-A host and Micro-USB device connectors.
ESP32-S3 AI Acceleration and Vector Instructions
This is where the ESP32-S3 truly differentiates itself. Espressif added vector instructions specifically designed to accelerate neural network inference and digital signal processing.
What Are ESP32-S3 Vector Instructions?
The LX7 cores in the ESP32-S3 include SIMD (Single Instruction, Multiple Data) extensions. Instead of processing one multiplication at a time, these instructions handle multiple operations in parallel.
For AI workloads, this matters enormously. Neural networks are fundamentally massive matrix multiplications—exactly the type of operation SIMD accelerates.
According to Espressif’s benchmarks:
16-bit face recognition runs approximately 6.25x faster with AI acceleration
8-bit quantized models see roughly 2.5x speedup
ESP32-S3 AI Software Libraries
Espressif provides several libraries that leverage these vector instructions:
Library
Purpose
Key Features
ESP-DL
Deep Learning inference
Face detection, recognition, hand pose
ESP-NN
Neural network primitives
Optimized operators for TFLite Micro
ESP-DSP
Digital signal processing
FFT, FIR filters, convolution
ESP-WHO
Computer vision framework
Pre-trained models, camera interface
ESP-Skainet
Voice assistant SDK
Wake word detection, speech commands
The ESP-DL library deserves particular attention. It provides pre-trained models for human face detection and recognition, cat face detection, and more experimental features like color detection and hand-pose estimation.
Running TinyML on ESP32-S3
TinyML—machine learning for microcontrollers—is where the ESP32-S3 excels compared to traditional IoT chips. With proper quantization (converting models to 8-bit integers), you can run meaningful AI inference directly on the device.
Practical TinyML applications I’ve successfully deployed on ESP32-S3 include:
Gesture Recognition: Using an accelerometer (like MPU6500), classify hand movements for touchless interfaces. Train models in Edge Impulse, deploy via TensorFlow Lite Micro.
Anomaly Detection: Monitor sensor patterns to detect equipment failures before they happen. The ESP32-S3 can run inference at hundreds of samples per second while consuming under 1W.
Wake Word Detection: Implement custom voice triggers without cloud connectivity. Privacy-preserving and low-latency.
Image Classification: With the XIAO ESP32S3 Sense or ESP32-S3-EYE, build real-time object detection systems. FOMO (Faster Objects, More Objects) from Edge Impulse works particularly well on these platforms.
ESP32-S3 Development Boards for USB OTG and AI Projects
Choosing the right development board can save considerable time. Here are proven options:
ESP32-S3 Development Board Comparison
Board
PSRAM
Camera
Display
USB
Best For
ESP32-S3-DevKitC-1
Optional
No
No
Native
General development
ESP32-S3-USB-OTG
8MB
No
1.3″ LCD
Host + Device
USB application development
ESP32-S3-EYE
8MB
2MP OV2640
LCD
Serial/JTAG
Computer vision
XIAO ESP32S3 Sense
8MB
OV2640/OV5640
No
Native
Compact AI cameras
ESP32-S3-BOX
16MB
No
2.4″ LCD
Native
Voice assistant prototyping
For USB OTG work specifically, the ESP32-S3-USB-OTG development board provides everything needed: separate host and device connectors, built-in USB switching, SD card slot, and an LCD display for debugging.
For AI and TinyML projects, boards with PSRAM are essential. Image processing and neural network inference consume significant memory—the internal 512KB SRAM won’t suffice for camera applications.
Getting Started with ESP32-S3 Development
The ESP32-S3 works well with multiple development environments. You can program it using Arduino, PlatformIO, or Espressif’s native ESP-IDF framework.
ESP32-S3 Programming Environment Setup
ESP-IDF (Recommended for USB OTG and AI)
ESP-IDF provides full access to hardware features and is required for advanced USB Host functionality. Install version 5.x or later for complete ESP32-S3 support.
Arduino IDE
Add the ESP32 board package via the Boards Manager. The arduino-esp32 core version 2.x supports most ESP32-S3 features, though some USB Host functionality requires ESP-IDF.
PlatformIO
Platform-agnostic development with good ESP32-S3 support. Useful for USB CDC/JTAG logging configuration.
Essential Configuration for ESP32-S3
When starting a project, enable these options in your SDK configuration:
PSRAM: Enable if your board has external PSRAM (required for camera/AI applications)
USB Configuration: Select between USB_SERIAL_JTAG and USB OTG peripheral
Flash Size: Configure based on your module (typically 8MB or 16MB)
Note that the internal USB PHY connects to USB_SERIAL_JTAG by default. Using the full USB OTG peripheral requires either an external PHY or burning the USB_PHY_SEL eFuse—which is permanent.
ESP32-S3 Real-World Project Ideas
Based on projects I’ve built and tested:
Smart Doorbell with Face Recognition: ESP32-S3-EYE board running ESP-WHO detects and recognizes faces, sends alerts via Wi-Fi. Complete system runs on USB power.
Predictive Maintenance Sensor: ESP32-S3 with accelerometer monitors industrial equipment vibration patterns. TinyML model detects anomalies and alerts maintenance staff before failures occur.
Wireless USB Hub: ESP32-S3-USB-OTG hosts multiple USB devices, provides network access to connected storage and peripherals.
Gesture-Controlled LED System: Accelerometer data processed by on-device ML model controls lighting without physical switches. Perfect for accessibility applications.
Can ESP32-S3 work as a USB host and device simultaneously?
No, the ESP32-S3 operates in one mode at a time. However, it can switch between modes dynamically. The ESP32-S3-USB-OTG development board includes switching circuitry to facilitate role changes.
How much faster is ESP32-S3 for AI compared to regular ESP32?
The AI vector instructions provide substantial acceleration. Espressif reports 6.25x improvement for 16-bit face recognition models and 2.5x for 8-bit quantized models. For general ML inference without vector optimization, expect roughly 2-3x improvement from the LX7 cores alone.
Does ESP32-S3 support Bluetooth Classic?
No. The ESP32-S3 only supports Bluetooth Low Energy 5.0 (including long-range coded PHY and 2 Mbps mode). Only the original ESP32 supports Bluetooth Classic for audio streaming and similar applications.
What external memory does ESP32-S3 support?
The ESP32-S3 supports high-speed octal SPI flash and PSRAM. This is a significant improvement over previous variants that only supported quad SPI. Modules with 8MB or 16MB flash and 8MB PSRAM are commonly available.
Is ESP32-S3 suitable for battery-powered applications?
Yes. The ESP32-S3 includes an ultra-low-power (ULP) coprocessor with both RISC-V and FSM variants. Light sleep and deep sleep modes allow extended battery operation while maintaining RTC functions and GPIO wake-up capability.
Conclusion: When Should You Choose ESP32-S3?
The ESP32-S3 makes the most sense when you need:
USB OTG functionality (host or device mode)
On-device AI/ML inference without cloud dependency
Camera or image processing capabilities
More GPIO than the original ESP32 provides
BLE 5.0 with long-range or high-throughput modes
For simpler IoT applications where these features aren’t required, the ESP32-C3 (RISC-V, lower cost) or ESP32-C6 (Wi-Fi 6, Thread/Matter) may be more appropriate choices.
But for anything involving computer vision, edge AI, or USB connectivity, the ESP32-S3 is currently the most capable option in Espressif’s lineup. The combination of dual cores, AI acceleration, and USB OTG in a sub-five-dollar module is genuinely remarkable.
Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Notes: For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.
