TTGO T-Watch
Smartwatch-style ESP32 board with display, battery, and sensors - great for wearable IoT and portable dashboards.
TTGO T-Watch Pinout
18 pins| Pin | GPIO | Labels | Status | Capabilities | Notes |
|---|---|---|---|---|---|
| 1 | 1 | TXPWM | uart | uart | |
| 2 | 2 | MISOPWM | strapping | spi | |
| 3 | 3 | RXPWM | uart | uart | |
| 4 | 13 | SSPWM | strapping | spi | |
| 5 | 14 | SCKPWM | strapping | spi | |
| 6 | 15 | MOSIPWM | strapping | spi | |
| 7 | 21 | SDAPWM | safe | i2c | |
| 8 | 22 | SCLPWM | safe | i2c | |
| 9 | 23 | TP_SDAPWM | safe | - | |
| 10 | 25 | DAC1PWM | safe | dac | |
| 11 | 26 | DAC2PWM | safe | dac | |
| 12 | 32 | TP_SCLPWM | safe | - | |
| 13 | 33 | TX1PWM | safe | - | |
| 14 | 34 | RX1 | strapping | - | |
| 15 | 35 | APX20X_INT | strapping | - | |
| 16 | 37 | RTC_INT | strapping | - | |
| 17 | 38 | TP_INT | strapping | - | |
| 18 | 39 | BMA42X_INT1 | strapping | - |
Start with these
7 pins with no boot or system involvementFreely assignable - no strapping, flash, USB or JTAG duties. Ideal first picks for buttons, sensors and LEDs.
Fine - with a little care
11 pins · 8 things to knowTXGPIO1 Default UART0 TX pin for USB-serial programming and console. UART
Connected to on-board USB-UART for uploading and logs; drives serial output at boot, so using as GPIO can disrupt programming or console.
MISOGPIO2 Bootstrapping pin (must be low or floating at reset); internal pull-down. Strapping
If driven HIGH on reset (while IO0 is LOW), selects an unsupported SDIO boot mode, causing boot failure.
RXGPIO3 Default UART0 RX pin for USB-serial programming (console input). UART
Used for receiving data from USB-UART (programming); also pulled HIGH at boot for console communication, so using as GPIO can disrupt uploads.
SSGPIO13 JTAG clock pin (TCK); also ADC2 channel 4 / Touch4 input. JTAG
Used for JTAG debugging (TCK); avoid using as GPIO if JTAG is needed.
SCKGPIO14 JTAG mode select pin (TMS); also HSPI CLK and PWM-capable GPIO. JTAG
Used for JTAG debugging (TMS); driving it as GPIO may interfere with JTAG or produce spurious signals at boot.
MOSIGPIO15 Bootstrapping pin; JTAG TDO; controls UART0 boot log output; also HSPICS0 (secondary SPI CS). Strapping
Keep HIGH during boot (internal PU); if LOW on reset, bootloader log is silenced and boot mode may change.
RX1GPIO34 Input-only GPIO (no output driver); ADC1 channel 6. Other
Cannot be used as output (no drive capability); only suitable for analog/digital input.
APX20X_INTGPIO35RTC_INTGPIO37TP_INTGPIO38BMA42X_INT1GPIO39 Input-only GPIOs with ADC1 channels - no output driver Other
Cannot be used as output; only suitable for input.
- APX20X_INTInput-only GPIO (no output driver); ADC1 channel 7.
- RTC_INTInput-only GPIO (no output); ADC1 channel 1.
- TP_INTInput-only GPIO (no output); ADC1 channel 2.
- BMA42X_INT1Input-only GPIO (no output); ADC1 channel 3, Hall sensor VN.
All 18 pins on the TTGO T-Watch are usable GPIO.
Peripheral wiring is straightforward: I²C is mapped to SDA on GPIO21 and SCL on GPIO22; the SPI bus (MOSI, MISO, SCK, SS) is broken out in full; TX/RX on GPIO1 and GPIO3 cover serial logging and flashing.
Beyond plain digital I/O you get 2 true DAC outputs.
11 of the exposed pins carry boot-time or system duties on the ESP32 (TX, MISO, RX and 8 more) - check the guidance above before wiring anything to them. SDA, SCL, TP_SDA, DAC1 and 3 more are free of any such role - the safest first picks.
Getting started
flash your first firmware in ~2 minutesBoard: ESP32 Wrover Module Flash Size: 16MB (128Mb) Flash Mode: DIO PSRAM: QSPI PSRAM Partition Scheme: 16M Flash (3MB APP/9.9MB FATFS) Upload Speed: 921600
// toggle GPIO21 - wire an LED and resistor to it
void setup() {
pinMode(21, OUTPUT);
}
void loop() {
digitalWrite(21, HIGH); delay(500);
digitalWrite(21, LOW); delay(500);
}[env:twatch]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
upload_speed = 921600
board_build.arduino.memory_type = qio_qspi
build_flags = -DBOARD_HAS_PSRAMesp32dev - or type it after board =.esp32:
board: esp32dev
variant: esp32
framework:
type: esp-idf
psram:
mode: quad
speed: 80MHz
# blink - GPIO21
output:
- platform: gpio
pin: 21
id: led_out
light:
- platform: binary
name: "LED"
output: led_outesp32dev (same ids as PlatformIO).esptool.py --chip esp32 --port /dev/ttyACM0 \
--baud 921600 write_flash 0x1000 firmware.bin--port = your /dev/tty* (macOS/Linux) or COMx (Windows).Specifications
ESP32 · 47 × 40 mm · vs other ESP32 chips →Dimensions
About this board
Inside sits the ESP32 - a dual-core Xtensa with both Bluetooth Classic and BLE.
At $36.55 it's on the expensive side for an ESP32 board - most land around $20.
Only 18 GPIO are broken out, where most ESP32 boards manage about 24 - worth checking the pinout covers what you need.
Around the module: 8MB (QSPI) PSRAM, an IPS LCD 1.54" 240x240 display with touch, a microphone, a speaker, an amplifier (MAX98357A), a PCF8563 RTC, an IR transceiver, a motion sensor (BMA423), battery charging (AXP202) and Power buttons.
- Vibration motor for haptic feedback
- Built-in rechargeable Li-Po battery
- PDM microphone (SPM1423) added on V3 for voice control
- AXP202 PMU manages charging and power rails
Where to buy
prices are typical street pricesResources
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