ESP32-S3 Module

ESP32-S3 Module

A Feather-like ESP32-S3 dev board with USB-C, IP5306 battery charging, an onboard NeoPixel, and status LEDs.

This is a small, self-contained development board built around the ESP32-S3-WROOM-1U. The idea is a go-to prototyping board: drop in a LiPo, plug in USB-C, and you have a programmable ESP32-S3 with WiFi/BLE/Zigbee, a NeoPixel for quick visual feedback, and a full set of 2.54mm breakouts. I made it because my other ESP32 boards were either not ESP32-S3, had no USB, or needed an external FTDI adapter just to flash.

Build status: assembled and working. USB, charging, the NeoPixel, and the user LED have all been verified on the physical board. See proof/V1 for build photos and test results.

Custom Features

• ESP32-S3-WROOM-1U (N8, 8 MB flash) with WiFi/BLE/Zigbee and a U.FL connector for an external antenna
• IP5306 power path: USB-C charging plus a 5V boost from a single-cell LiPo, with an LED battery gauge
• TLV75733 3.3V LDO for the MCU and logic
• USB-C receptacle with USBLC6-2SC6 ESD protection and 5.1k CC resistors
• Onboard WS2812B NeoPixel and 7 orange status LEDs
• RESET and BOOT buttons, plus an IP5306 power key
• Flashing over the ESP32-S3 native USB or over UART/FTDI through the headers
• 2.54mm header breakouts and a JST-PH battery connector

How It Works

The board is four functional blocks plus a breakout. USB-C feeds the IP5306, which charges the LiPo and boosts it to a 5V rail. That rail powers the NeoPixel and feeds a TLV75733 LDO, which makes the 3.3V rail for the ESP32-S3. The MCU drives the NeoPixel on GPIO47 and the user LED on GPIO48, and breaks out its remaining IO on the two headers.

Power Tree

flowchart LR
  USB["USB-C VBUS"] --> IP5306["IP5306 (U2)"]
  BATT["LiPo JST-PH (J2)"] <--> IP5306
  IP5306 -->|+5V| NEO["WS2812B NeoPixel (D8)"]
  IP5306 -->|+5V| LDO["TLV75733 LDO (U3)"]
  LDO -->|+3.3V| ESP["ESP32-S3-WROOM-1U (U4)"]
  ESP -->|GPIO47| NEO
  ESP -->|GPIO48| LED["User LED (D7)"]

PCB Design

The board is a 4-layer PCB measuring 35.70 x 79.00 mm, with 1.6mm thickness and a dedicated ground inner layer. Power traces are widened and the edges are rounded for handling. Routing is done by hand in KiCad.

Schematic and PCB sources live in kicad/. Fabrication outputs (Gerbers, drill, BOM, pick-and-place) are in kicad/production/, and the STEP model is in cad/.

Build

The board was assembled by hand: parts laid out and checked, the USB-C and power sections soldered first, then the headers and the JST-PH battery connector. After that came the power-on checks over USB-C and a power bank.

The NeoPixel and status LEDs running the self-test: video/neopixel.mp4.

More build and test detail: proof/V1/PROOF.md.

Firmware

The firmware in firmware/ is an interactive self-test over USB CDC. It reports system info and power status, drives the NeoPixel and user LED, reads the BOOT button, runs a GPIO loopback check, and scans for WiFi and BLE networks. It is a PlatformIO project using the Arduino framework, the Adafruit NeoPixel library, and NimBLE-Arduino.

cd firmware
pio run                 # build
pio run --target upload # flash over USB

To enter the bootloader manually:

1. Hold BOOT (SW2 / IO0)
2. Tap RESET (SW3 / EN)
3. Release BOOT
4. Start the upload

See firmware/README.md for the pin map and library details.

Usage

Power

• Charging: plug a USB-C cable into J1. The IP5306 charges the LiPo through J2 and lights the charge gauge.
• Battery: connect a single-cell LiPo to the JST-PH connector (J2).
• The IP5306 power key (SW1) turns the 5V/3.3V rails on and off.

Programming

• Native USB: connect USB-C and flash the ESP32-S3 directly (GPIO19/GPIO20).
• UART/FTDI: use TXD0 (J4 pin 18) and RXD0 (J4 pin 17) with GND, then trigger BOOT/RESET.

Pinout

J3 - 1x22 header:

J4 - 1x21 header:

Note: IO0, IO3, IO45, IO46 are ESP32-S3 strapping pins. Pull them the wrong way at boot and the chip enters a different mode.

BOM

Full BOM with LCSC part numbers, manufacturers, and supplier links: BOM.csv. KiCad-generated BOM and pick-and-place: kicad/production/bom.csv, kicad/production/positions.csv.

Production

The board is designed for JLCPCB's standard 4-layer process:

• 4 layers, 1.6mm thick
• HASL lead-free finish
• Gerbers and drill files: kicad/production/ESP32-S3_Module.zip

Repository Structure

.
|-- BOM.csv                 # Full bill of materials with supplier links
|-- README.md
|-- JOURNAL.md              # Build journal
|-- TIMELINE.md
|-- TODO.md                 # Ideas for v2
|-- cad/                    # STEP model
|-- firmware/               # PlatformIO firmware (Arduino)
|-- images/                 # Schematic, PCB, and render images
|-- kicad/                  # KiCad sources and production outputs
|-- proof/                  # Build and test proof
|-- LICENSE                 # CERN-OHL-P-2.0 (hardware)
`-- LICENSE-MIT             # MIT (firmware)

Known Issues

• WiFi, Bluetooth, and Zigbee have not been exercised yet. The self-test includes WiFi and BLE scan menus, but the radio results have not been confirmed on this board.
• The module uses a U.FL connector instead of an onboard antenna, so an external 2.4 GHz antenna is required for radio range.
• The current layout has DRC issues that should be cleaned up in v2: 2 shorting-item errors and 6 clearance errors around the ESP32 module footprint, plus 3 library footprint mismatch warnings. These are flagged in the committed PCB and did not stop the board from working, but they are not intentional.
• USB-C CC lines are 5.1k sink resistors, so the board draws power but does not negotiate anything above the default USB current.

Credits & Inspiration

• Form factor inspired by the Adafruit Feather line.
• The IP5306 power section was adapted from my own earlier IP5306-based projects.
• Built with KiCad and PlatformIO.
• Firmware uses the Adafruit NeoPixel library.
• Espressif ESP32-S3 datasheets and the ESP32-S3 Hardware Design Guidelines.

License

• Hardware (schematics, PCB, and CAD): CERN Open Hardware Licence Version 2 - Permissive. SPDX: CERN-OHL-P-2.0. See LICENSE.
• Firmware (firmware/): MIT License. SPDX: MIT. See LICENSE-MIT.