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Espressif ESP32-S3-USB-Bridge
USB-to-serial debug board with ESP32-S3 - ideal for interfacing with and debugging ESP-based modules via USB.
31.5 × 23.3 mm
ESP32-S3
MCU
240MHz
clock
4MB
flash
512KB
SRAM
12· 1 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
12 pins
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 0 | A0T0PWM | strapping | adc · touch | |
| 2 | 2 | TDOPWM | safe | - | |
| 3 | 3 | TDIPWM | strapping | - | |
| 4 | 4 | TCKPWM | safe | - | |
| 5 | 5 | TMSPWM | safe | - | |
| 6 | 8 | Reset | safe | - | |
| 7 | 9 | Boot | strapping | - | |
| 8 | 19 | USB_D- | uart | - | |
| 9 | 20 | USB_D+ | uart | - | |
| 10 | 40 | RX | strapping | uart | |
| 11 | 41 | TX | strapping | uart | |
| 12 | 42 | WS2812 | strapping | - |
Start with these
4 pins with no boot or system involvementTDOPWMTCKPWMTMSPWMReset
Freely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
sampled at boot or shared with debug/serial| Pin | Label | What to know | Role |
|---|---|---|---|
| A0 | GPIO0 | Must be pulled high (default) or low (to enter UART download mode) at reset. Using it for other functions can interfere with boot mode configuration. | Strapping |
| TDI | GPIO3 | Sampled at reset to select JTAG interface (USB Serial/JTAG controller vs. external pins). Improper use can disable external JTAG or alter debug interface. | Strapping |
| RX | MTDO (GPIO40) | Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality. | Other |
| TX | MTDI (GPIO41) | Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available. | Other |
| WS2812 | MTMS (GPIO42) | Default JTAG TMS signal for debugging. Using this pin for other purposes will disable the JTAG interface (unless JTAG is rerouted to USB). | Other |
Only if you know the tricks
wired to flash or USB - expect a fight| Pin | Label | What to know | Role |
|---|---|---|---|
| Boot | FSPIHD | Connected to external flash (data/hold signal) on most modules. Not recommended for use as GPIO, since it must remain dedicated to flash communication. | Flash |
| USB_D- | USB_D- | By default connected to the on-chip USB Serial/JTAG controller. Using it as general GPIO without reconfiguring IO MUX will interfere with USB functionality. | USB |
| USB_D+ | USB_D+ | By default connected to the on-chip USB Serial/JTAG controller. Using it as general GPIO without reconfiguring IO MUX will interfere with USB functionality. | USB |
These are recommendations, not hard rules - with the right pull-ups, timing and boot-state awareness most pins can be made to work. When in doubt, start green.
Pinout notes All 12 pins on the Espressif ESP32-S3-USB-Bridge are usable GPIO. Peripheral wiring is straightforward: TX / RX on GPIO41 and GPIO40 cover serial logging and…
All 12 pins on the Espressif ESP32-S3-USB-Bridge are usable GPIO.
Peripheral wiring is straightforward: TX/RX on GPIO41 and GPIO40 cover serial logging and flashing.
Beyond plain digital I/O you get 1 ADC-capable pins for sensors and battery monitoring and 1 capacitive-touch inputs.
5 of the exposed pins carry boot-time or system duties on the ESP32-S3 (A0, TDI, RX and 2 more) - check the guidance above before wiring anything to them. TDO, TCK, TMS and Reset are free of any such role - the safest first picks.
The ESP32-S3-USB-Bridge features a 12-pin expansion connector providing access to key GPIOs and communication interfaces. Key pins include power supply (3V3 and GND), JTAG pins (TCK, TMS, TDI, TDO), UART pins (TX, RX), and control pins (Boot, Reset). This configuration allows for seamless integration with target chips and peripherals.
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Native USB - no driver, no serial chip. Not detected? Hold BOOT while plugging in.
2
Flash with your tool
Arduino IDE, PlatformIO, ESPHome or esptool - copy the settings on the right.
3
Verify it runs
The blink example uses GPIO2 - swap for your board's LED pin if different.
Board: Esp32 S3 Usb Bridge
USB CDC On Boot: Enabled
Flash Size: 4MB · DIO
Upload Speed: 921600
// blink
pinMode(2, OUTPUT);
digitalWrite(2, LOW); // on (often inverted)[env:esp32-s3-usb-bridge]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600esp32:
board: esp32-s3-devkitc-1
variant: esp32_s3_usb_bridge
framework:
type: esp-idf
# blink - GPIO2
output:
- platform: gpio
pin: 2
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesptool.py --chip esp32s3 --port /dev/ttyACM0 \
write_flash 0x0 firmware.binBuild details: sketch space 2097152 B · data 327680 B · DIO
Specifications
ESP32-S3 · 31.5 × 23.3 mmCompute
MCU
ESP32-S3
Clock
240 MHz
SRAM · Flash
512 KB · 4MB · 2MB (QSPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
5.0 LE
Antenna
PCB
I/O
GPIO · ADC
12 · 1
UART · I²C · SPI
3 · 2 · 4
PWM
8 channels
Power
USB
USB-C (native) · USB-A
Serial
Native (CDC)
Boot address
0x0
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · DIO
Sketch · Data
2 MB · 320 KB
31.5 × 23.3 mm
The Espressif ESP32-S3-USB-Bridge uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with DIO boot mode. The maximum sketch size is 2 MB with 320 KB available for data.
About this board
Inside sits the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
At $9.99 it's cheaper than most ESP32-S3 boards, which usually run around $30.
Only 12 GPIO are broken out, where most ESP32-S3 boards manage about 21 - worth checking the pinout covers what you need.
Around the module: 2MB (QSPI) PSRAM, an addressable RGB LED (GPIO42) and Boot/Reset buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
The ESP32-S3-USB-Bridge is a compact development board based on the ESP32-S3-MINI-1 module. It serves as an alternative to traditional USB-to-UART chips by establishing a bridge between a computer and existing microcontrollers. The board supports multiple functions, including USB-to-UART bridging, JTAG debugging, and acts as a USB composite device supporting various functionalities.
Where to buy
prices are typical street pricesEspressif ESP32-S3-USB-Bridge
$9.99per unit, typical
Resources
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