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LilyGo T4-S3
A versatile ESP32-S3 board by LilyGo, suitable for a wide range of IoT and embedded projects.
56 × 44 mm
ESP32-S3
MCU
240MHz
clock
16MB
flash
512KB
SRAM
16· 6 ADC
GPIO
BLE 5.0+ WiFi
radio
Pinout
20 pins
| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | - | 3V33.3V | power | - | 3.3V power - 2x15 header and both Qwiic connectors |
| 2 | - | VBUS5V | power | - | 5V from USB-C (VBUS) - 2x15 header |
| 3 | - | BATVBAT | power | - | Battery voltage (VBAT) - 2x15 header |
| 4 | - | GND | ground | - | Ground - 2x15 header and both Qwiic connectors |
| 5 | 1 | IO1SD_CS | safe | adc · touch · spi | microSD chip select - 2x15 header (shared with microSD slot) |
| 6 | 2 | IO2SD_MOSI | safe | adc · touch · spi | microSD MOSI - 2x15 header (shared with microSD slot) |
| 7 | 3 | IO3SD_SCK | strapping | adc · touch · spi | microSD SCK - 2x15 header (shared with microSD slot) |
| 8 | 4 | IO4SD_MISO | safe | adc · touch · spi | microSD MISO - 2x15 header (shared with microSD slot) |
| 9 | 6 | SDAIO6 | safe | adc · touch · i2c | I2C SDA - 2x15 header and Qwiic (shared with CST226SE touch and SY6970 PMU) |
| 10 | 7 | SCLIO7 | safe | adc · touch · i2c | I2C SCL - 2x15 header and Qwiic (shared with CST226SE touch and SY6970 PMU) |
| 11 | 21 | IO21 | safe | - | Free GPIO - 2x15 header |
| 12 | 38 | IO38 | safe | - | Free GPIO - 2x15 header |
| 13 | 39 | IO39 | strapping | - | Free GPIO - 2x15 header |
| 14 | 40 | IO40 | strapping | - | Free GPIO - 2x15 header |
| 15 | 41 | IO41 | strapping | - | Free GPIO - 2x15 header |
| 16 | 42 | IO42 | strapping | - | Free GPIO - 2x15 header |
| 17 | 43 | TXDIO43 | strapping | uart | UART0 TX - 2x15 header and UART Qwiic connector |
| 18 | 44 | RXDIO44 | strapping | uart | UART0 RX - 2x15 header and UART Qwiic connector |
| 19 | 47 | IO47 | strapping | - | Free GPIO - 2x15 header |
| 20 | 48 | IO48 | strapping | - | Free GPIO - 2x15 header |
Start with these
7 pins with no boot or system involvementIO1SD_CSIO2SD_MOSIIO4SD_MISOSDAIO6SCLIO7IO21IO38
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 |
|---|---|---|---|
| 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 |
| IO39 | MTCK (GPIO39) | Default JTAG TCK - keep it free if you debug over JTAG. It is not a flash or PSRAM line on standard modules: those sit on GPIO26-37. | Other |
| IO40 | MTDO (GPIO40) | Default JTAG TDO output for debugging. Using it as GPIO will interfere with JTAG debugging functionality. | Other |
| IO41 | MTDI (GPIO41) | Default JTAG TDI input for debugging. Should be reserved for JTAG or left unused if JTAG is to remain available. | Other |
| IO42 | 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 |
| TXD | U0TXD (GPIO43) | Used for bootloader output and UART console logs. If repurposed, you will lose the default serial output (and programming via UART0). | Other |
| RXD | U0RXD (GPIO44) | Used for bootloader input (download mode via serial). If repurposed, you cannot use the default UART0 download mode for programming the chip. | Other |
| IO47 | SPICLK_P | Only the 1.8 V octal parts (ESP32-S3R8V, ESP32-S3R16V) run the differential memory clock here, and on those the pin works at 1.8 V instead of 3.3 V. On the common 3.3 V modules it is a normal GPIO - several devkits drive their RGB LED from GPIO48. | Other |
| IO48 | SPICLK_N | Only the 1.8 V octal parts (ESP32-S3R8V, ESP32-S3R16V) run the differential memory clock here, and on those the pin works at 1.8 V instead of 3.3 V. On the common 3.3 V modules it is a normal GPIO - several devkits drive their RGB LED from GPIO48. | Other |
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 The LilyGo T4-S3 breaks out 20 pins in total: 16 GPIO for your project, with 3V3, VBUS, BAT and GND handling power. For peripherals, I²C is mapped to SDA on…
The LilyGo T4-S3 breaks out 20 pins in total: 16 GPIO for your project, with 3V3, VBUS, BAT and GND handling power.
For peripherals, I²C is mapped to SDA on GPIO6 and SCL on GPIO7.
On the analog side there are 6 ADC-capable pins for sensors and battery monitoring and 6 capacitive-touch inputs.
If you want zero surprises, IO1, IO2, IO4, SDA and 3 more are free of any such role - the safest first picks. 9 of the exposed pins carry boot-time or system duties on the ESP32-S3 (IO3, IO39, IO40 and 6 more).
Getting started
flash your first firmware in ~2 minutes1
Connect over USB
Native USB - shows up as a port right away, no driver needed. Not detected? Hold BOOT while plugging in.
2
Match & flash
Set the Tools options shown, then click Upload.
3
Verify it runs
GPIO1 toggles - wire an LED and resistor to it, or change the pin to your board's own LED.
Set these in Tools · leave everything else at default
Arduino IDE 2.x - Tools Copy
Board: "ESP32S3 Dev Module"▸
USB CDC On Boot: "Enabled"▸
Flash Size: "16MB (128Mb)"▸
Flash Mode: "DIO"▸
PSRAM: "OPI PSRAM"▸
Partition Scheme: "16M Flash (3MB APP/9.9MB FATFS)" (default)▸
Upload Speed: "921600"▸
▸ every other Tools option - leave at default
Board: ESP32S3 Dev Module USB CDC On Boot: Enabled Flash Size: 16MB (128Mb) Flash Mode: DIO PSRAM: OPI PSRAM Partition Scheme: 16M Flash (3MB APP/9.9MB FATFS) Upload Speed: 921600
Find it: Tools ▸ Board ▸ ESP32 Arduino ▸ ESP32S3 Dev Module
// toggle GPIO1 - wire an LED and resistor to it
void setup() {
pinMode(1, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH); delay(500);
digitalWrite(1, LOW); delay(500);
}board to selectesp32-s3-devkitc-1⧉ copy
[env:lilygo_t4_s3]
platform = espressif32
board = esp32-s3-devkitc-1
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_opi
build_flags = -DBOARD_HAS_PSRAMFind it: PlatformIO Home ▸ Boards, search
esp32-s3-devkitc-1 - or type it after board =.board to selectesp32-s3-devkitc-1⧉ copy
esp32:
board: esp32-s3-devkitc-1
variant: esp32s3
framework:
type: esp-idf
psram:
mode: octal
speed: 80MHz
# blink - GPIO1
output:
- platform: gpio
pin: 1
id: led_out
light:
- platform: binary
name: "LED"
output: led_outFind it: search ESPHome's board list for
esp32-s3-devkitc-1 (same ids as PlatformIO).esptool doesn't pick board settings - a prebuilt .bin already has them baked in. This is just the raw flash command.
esptool.py --chip esp32s3 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x0 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Build details: sketch space 3145728 B · data 327680 B · DIO
Specifications
ESP32-S3 · 56 × 44 mm · vs other ESP32 chips →Compute
MCU
ESP32-S3
Clock
240 MHz
SRAM · Flash
512 KB · 16MB · 8MB (OPI) PSRAM
Radio
Wi-Fi
802.11 b/g/n
Bluetooth
5.0 LE
Antenna
u.FL
I/O
GPIO · ADC
16 · 6
UART · I²C · SPI
3 · 2 · 2
PWM
8 channels
Power
USB
USB-C
Serial
Native (CDC)
Boot address
0x0
Display
Screen
AMOLED · 2.41" · 450x600
Driver
RM690B0
Touch
CST226SE
Flashing
Upload · OTA
esptool_py · esp_ota
Flash · Boot mode
DIO · QIO
Sketch · Data
3 MB · 320 KB
56 × 44 mm
The LilyGo T4-S3 uses esptool_py for firmware uploads, esp_ota for over-the-air (OTA) updates. Flash mode is DIO with QIO boot mode. The maximum sketch size is 3 MB with 320 KB available for data.
About this board
At its core is the ESP32-S3 - a dual-core Xtensa with vector extensions suited to AI workloads.
Expect to pay about $58.99 - above the ~$29 typical for ESP32-S3 boards.
Only 16 GPIO are left for your own hardware - the display and onboard peripherals claim the rest.
Onboard you'll find 8MB (OPI) PSRAM, an AMOLED 2.41" 450x600 display with touch, battery charging (SY6970) via JST 1.25mm and Reset/Boot buttons.
It flashes over native USB - no serial-converter driver needed, which isn't a given among ESP32-S3 boards.
The LilyGo T4-S3 is an ESP32-S3-based development board designed for high-performance IoT applications. Featuring a large 2.41-inch AMOLED display and low-power consumption, it is ideal for smart display projects.
With WiFi 802.11 b/g/n and Bluetooth 5 (LE), it supports seamless wireless communication, making it perfect for remote monitoring and embedded systems.
The T4-S3 comes with 8MB PSRAM and 16MB Flash, providing ample memory for complex applications.
Where to buy
prices are typical street pricesLilyGo T4-S3
$58.99per unit, typical
Resources
Board datasheet lilygo.cc↗ ESP32-S3 datasheet espressif.com↗ LilyGo T4-S3 product page lilygo.cc↗LilyGo AMOLED Series (GitHub, driver & touch support) github.com↗CNX Software - T4-S3 review cnx-software.com↗LilyGo-AMOLED-Series src/LilyGo_AMOLED.h (T4-S3 RM690B0 QSPI + CST226SE pin map) github.com↗LilyGo-AMOLED-Series T4-S3 schematic (PDF) github.com↗
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