LilyGo T-Watch S3

Development Board

Code name: LILYGO_T_WATCH_S3

LilyGo T-Watch S3 is a development board based on the ESP32S3 microcontroller using XTENSA architecture.

This board features a maximum CPU frequency of 240 MHz and 16MB flash memory.

About LilyGo T-Watch S3

🚀 The LilyGo T-Watch S3 is an ESP32-S3-powered smartwatch development kit designed for wearable applications. It features a 1.54-inch IPS LCD touch screen, a built-in rechargeable battery, and a variety of sensors, making it perfect for smart wearable projects. ⚡

📡 With integrated WiFi 802.11 b/g/n and Bluetooth 5 (LE), it enables seamless wireless connectivity for IoT applications.

💾 Equipped with 8MB PSRAM and 16MB Flash, the T-Watch S3 is ideal for running complex applications, including graphical interfaces and real-time monitoring.

Technical Specifications

Complete technical specification details for LilyGo T-Watch S3

Display

Type Touch

Size 1.54"

Resolution 240x240

Driver ST7789V

Connectivity

WiFi 802.11 b/g/n (2.4 GHz)

Bluetooth 5.0

BLE 5.0

Microcontroller

Model esp32s3

Clock Speed 240 MHz

Flash Size 16MB

PSRAM 8MB

Architecture xtensa

✨ Features & Pins

Digital IO 48

Analog Input 20

PWM 27

Interrupts 46

Download Full Datasheet

Quick Setup

Copy-paste configs for LilyGo T-Watch S3 - auto‑generated from this board's exact hardware specs.

ESP32S3 240 MHz 16MB DIO Xtensa

In Arduino IDE 2 select Lilygo T Watch S3 from the esp32 by Espressif package. In PlatformIO use board = esp32-s3-devkitm-1. ESP32S3 · 240 MHz · 16MB · DIO.

Tools menu settings

Board (select in Arduino IDE) Lilygo T Watch S3

CPU Frequency 240 MHz

Flash Size 16MB

Flash Mode DIO

Upload Speed 921600

Architecture Xtensa

In Arduino IDE 2, open Boards Manager, search "esp32" by Espressif and install it. Then go to Tools → Board and select "Lilygo T Watch S3" for the LilyGo T-Watch S3.

platformio.ini


[env:lilygo_t_watch_s3]
platform  = espressif32
board     = esp32-s3-devkitm-1
framework = arduino

; Exact hardware config for LilyGo T-Watch S3
board_build.mcu        = esp32s3
board_build.f_cpu      = 240000000L
board_build.flash_size = 16MB
board_build.flash_mode = dio
board_upload.flash_size = 16MB

The board value is a close generic match - check PlatformIO board registry for an exact fit.

esp32: block (YAML)


esp32:
  board: esp32-s3-devkitc-1
  framework:
    type: arduino   # or "esp-idf"

# LilyGo T-Watch S3 - 240 MHz ESP32S3
# Flash: 16MB | USB: N/A

Paste into your device's .yaml. See ESPHome ESP32 docs for full options.

esptool.py - flash command


esptool.py \
  --chip esp32s3 \
  --baud 921600 \
  write_flash \
    --flash_mode dio \
    --flash_size 16MB \
    0x0 bootloader.bin \
    0x8000    partitions.bin \
    0xe000    boot_app0.bin \
    0x10000   firmware.bin

Install: pip install esptool - replace firmware.bin with your binary - bootloader at 0x0

LilyGo T-Watch S3 Pinout Diagram

Complete pin reference for LilyGo T-Watch S3

Safe Pins to Use

These pins are safe for general GPIO usage without boot or system conflicts

IO1

IO2

IO16

IO17

IO18

IO21

IO22

IO23

IO25

IO26

IO27

Why Are These Pins Safe?

✓ No boot sequence involvement

✓ No flash/PSRAM connections

✓ No USB or JTAG conflicts

✓ Freely assignable without issues

Pins to Avoid or Use with Caution

Reserved for critical functions. Misuse may cause boot failures, programming issues, or system conflicts.

Strapping Pins

Boot behavior & flash voltage

JTAG Debugging

Low-level debugging interface

USB Pins

USB Serial/JTAG communication

Flash/SPI Pins

Memory & PSRAM connections

UART Serial

Debugging & firmware uploads

PIN	Label	Why Avoid	Type
IO3	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
IO19	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

Useful Links

Datasheets and resources for LilyGo T-Watch S3

Board Datasheet

Technical specifications

ESP32S3 Datasheet

Microcontroller reference

LilyGo T-Watch S3 Custom Pin Mapping

Pin configuration and GPIO mapping for LilyGo T-Watch S3

Digital I/O Pins

Interrupt Pins

Analog Inputs

PWM Pins

Pin	Function	ESP Pin	I/O Type	Description
1	3V3	3.3V	POWER OUTPUT	3.3V power output
2	GND	GND	POWER GROUND	Ground connection
3	5V	5V	POWER INPUT	5V power input
4	IO1	GPIO1	BIDIRECTIONAL	GPIO, ADC, I2C
5	IO2	GPIO2	BIDIRECTIONAL	GPIO, ADC
6	IO3	GPIO3	BIDIRECTIONAL	GPIO, ADC
7	IO16	SPI_CS	BIDIRECTIONAL	GPIO, SPI Chip Select
8	IO17	SPI_D	BIDIRECTIONAL	GPIO, SPI Data
9	IO18	SPI_CLK	BIDIRECTIONAL	GPIO, SPI Clock
10	IO19	SPI_Q	BIDIRECTIONAL	GPIO, SPI Q
11	IO21	LCD_DC	OUTPUT	GPIO, LCD Data/Command
12	IO22	LCD_RST	OUTPUT	GPIO, LCD Reset
13	IO23	LCD_BL	OUTPUT	GPIO, LCD Backlight
14	IO25	TOUCH_SDA	BIDIRECTIONAL	GPIO, I2C Data for Touch
15	IO26	TOUCH_SCL	BIDIRECTIONAL	GPIO, I2C Clock for Touch
16	IO27	BUTTON	INPUT	GPIO, User Button

Legend

Function Pin role

GPIO ESP32 pin

I/O Direction

# Pin number

Default Tools & Configuration

Build and upload settings for LilyGo T-Watch S3

Setting	Value
Bootloader tool	esptool_py
Uploader tool	esptool_py
Network uploader tool	esp_ota
Bootloader address	`0x0`
Flash mode	dio
Boot mode	qio
PSRAM type	opi
Maximum upload size	3072 KB (3145728 bytes)
Maximum data size	320 KB (327680 bytes)