ESP32 GPIO1

GPIO1 / U0TXD / CLK_OUT3

Use with care - Fine for many uses, but check the warnings below first.

What GPIO1 can do

Digital input/output
PWM output (LEDC)
UART (via GPIO matrix)

Warnings for GPIO1

UART0 / serial console

Default UART0, used for flashing and the serial monitor. On dev boards these two pins are wired to the onboard USB-to-serial chip. You can use them as GPIO, but you lose USB serial upload/debug, and GPIO1 (U0TXD) outputs the boot log at every reset.

Default UART0 TX. Busy during programming and outputs boot log at 115200 baud.

Open the interactive ESP32 pinout →

All ESP32 pins

GPIO0 · GPIO1 · GPIO2 · GPIO3 · GPIO4 · GPIO5 · GPIO6 · GPIO7 · GPIO8 · GPIO9 · GPIO10 · GPIO11 · GPIO12 · GPIO13 · GPIO14 · GPIO15 · GPIO16 · GPIO17 · GPIO18 · GPIO19 · GPIO21 · GPIO22 · GPIO23 · GPIO25 · GPIO26 · GPIO27 · GPIO32 · GPIO33 · GPIO34 · GPIO35 · GPIO36 · GPIO39

ESP32 Pinout Studio - free interactive pinout reference. Pin data generated from Espressif's official KiCad libraries. esp32pin.com