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
🛰️ Connectivity
🧠 Microcontroller
✨ Features & Pins
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
💡 Why Are These Pins Safe?
⚠️ Pins to Avoid or Use with Caution
Reserved for critical functions. Misuse may cause boot failures, programming issues, or system conflicts.
Boot behavior & flash voltage
Low-level debugging interface
USB Serial/JTAG communication
Memory & PSRAM connections
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
LilyGo T-Watch S3 Custom Pin Mapping
Pin configuration and GPIO mapping for LilyGo T-Watch S3
| 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 |
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) |
The LilyGo T-Watch S3 uses esptool_py for uploads , esp_ota for OTA updates, and esptool_py bootloader at 0x0.
Flash mode: dio | Boot mode: qio | PSRAM: opi
Max sketch size: 3072 KB | Max data size: 320 KB
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