ESP32-S3 powers EWatch smartwatch with open drivers and DIY options

Published on Vinjo by Vinay • EWatch is a programmable ESP32-S3 smartwatch featuring a 1.69-inch color touchscreen, open-source drivers, and versatile power management. Offered in bare PCB, self-assembly kit, or pre-built options, it provides a flexible hardware platform for DIY creators.

Quick Overview & Specifications

AttributeDetails
PublicationVinjo Engineering & Technology
CategoryHardware & IoT
AuthorVinay
Article TypeTechnical Tutorial & Case Study
Published2026-10-20
Last Updated2026-10-20
License / AccessOpen Educational Resource
Core Engineering Highlights:
  1. Verified hardware architecture, schematics, and pinout diagrams.
  2. Comprehensive firmware routines, protocol benchmarks, and build steps.
  3. Production design rules, tolerances, and thermal considerations.
Related Topic Taxonomy:
  • #ESP32-S3
  • #Smartwatch
  • #Open Hardware

ESP32-S3 powers EWatch smartwatch with open drivers and DIY options

Summary: The EWatch is a customizable, open-source smartwatch platform built around the ESP32-S3 microcontroller by developer Ewan Wills. Featuring a 1.69-inch color touchscreen, open drivers, and advanced power management circuitry, it provides options for raw PCB tinkering, full kit self-assembly, or ready-to-wear use.

Key Takeaways

  • Versatile Form Factors: Offered as a bare PCB (£59), a self-assembly kit (£99), or a fully pre-assembled device (£129) to support varying levels of hardware customization.
  • Open Software Ecosystem: Includes open-source drivers covering touch control, display rendering, IMU sensing, BLE, and low-power modes across Arduino IDE, PlatformIO, and ESP-IDF environments.
  • Advanced Power Management: Features an onboard latching power circuit for software-controlled power-down, active battery level monitoring, and persistent time retention while shut off.

Detailed Overview

Developed by Ewan Wills over more than five years of iteration and prototyping, EWatch is a fully programmable smartwatch powered by the Espressif ESP32-S3 microcontroller. Operating with integrated Wi-Fi and Bluetooth Low Energy (BLE) connectivity, the watch bridges open-source wearable hardware with accessible software drivers.

ESP32-S3 Block Diagram

The platform supports development across multiple popular micro-controller environments—including Arduino IDE, PlatformIO, and ESP-IDF—and lists software support for C, C++, Python, and Rust.

Hardware Architecture & Design

At the core of EWatch is a compact 34 × 28 mm two-layer PCB with an ENIG surface finish. To facilitate external component integration, the board exposes both I2C and UART communications headers in addition to the touch screen interface and a USB-C port.

EWatch PCB

The full watch hardware configuration includes:

  • Display: 1.69-inch full-color capacitive touchscreen.
  • Battery: 350 mAh rechargeable lithium cell.
  • Feedback: Integrated vibration motor for haptic alerts.
  • Enclosure: Custom housing with a standard 20 mm replaceable strap attachment.

Power Management & Prototyping History

The current revision follows multiple prototyping phases, evolving from breadboard wiring and hand-soldered boards to custom multi-layer PCB builds.

EWatch Kit

A significant portion of the hardware development focused on custom power management architecture, implementing:

  • Dedicated battery charging and voltage regulation.
  • Battery-level sensing and voltage monitoring.
  • A software-controlled latching power circuit allowing the board to turn itself off entirely.
  • Real-time clock retention to keep track of time while the main system remains powered down.

EWatch Demo

Deep Dive & Software Insights

The platform is structured to allow developers to interact with high-level APIs or directly control low-level peripherals when necessary. Open-source drivers are provided for key system functions, including touch input, display rendering, IMU orientation tracking, BLE stacks, charging circuitry, and sleep states.

EWatch Assembled

AI-Assisted Firmware Workflows

The project emphasizes rapid firmware prototyping using AI assistance. By providing driver documentation and hardware context to a Large Language Model (LLM), developers can prompt the creation of new applications—such as stopwatches, timers, or custom watch faces—and compile them directly to the board.

Additionally, an upcoming platform titled EWatch Cloud is planned to offer a browser-based development suite. This ecosystem will allow compiling and flashing firmware without local toolchain installation, while offering an integrated AI coding assistant and an app marketplace for sharing watch faces.

Hardware Specifications

Feature Specification
Processor Espressif ESP32-S3 (Dual-core RISC-V/Tensilica, Wi-Fi & BLE)
Display 1.69-inch color touchscreen
Connectivity & I/O USB-C, I2C, UART
Sensors & Haptics Inertial Measurement Unit (IMU), Vibration motor
Power Management 350 mAh battery, battery level sensing, charging circuit, software latching power switch
Mechanical Dimensions 34 × 28 mm PCB (2-layer ENIG finish), 20 mm replaceable watch strap

Future Roadmap: V2 Hardware Revision

An updated V2 hardware design is currently under development. Planned enhancements for the next revision include:

  • Integrated onboard microphone.
  • Dedicated fuel gauge IC for precise battery metering.
  • RGB notification LED.
  • Expansion to 16MB flash storage.
  • External u.FL antenna connector.

Conclusion & Resources

The EWatch delivers a versatile platform for wearable device development, combining flexible power management, open drivers, and multiple assembly options for makers and developers.

Resources