ESP32 WIRING GUIDE
Pick the pins.
Check the voltage.
A clean wiring plan starts before the first jumper wire.
GPIO FIRST
Not every pin is interchangeable.
ESP32 boards expose many GPIOs, but some pins may be used for boot configuration, flash, USB, onboard LEDs or other board-specific functions. Check the pinout for the exact board rather than assuming that a pin used on one ESP32 variant behaves the same on another.
For buses such as I2C and SPI, choose a sensible group of pins and keep the definitions together in the code. That makes a project easier to troubleshoot and move between boards.
VOLTAGE LEVELS
ESP32 GPIO is 3.3 V logic.
Do not feed a 5 V logic signal directly into a 3.3 V-only ESP32 input unless the exact board or device documentation says the pin is tolerant. A level shifter or suitable divider can translate signal voltage when a 5 V peripheral and a 3.3 V controller need to communicate.
A common example is a 5 V addressable LED strip. The data signal may sometimes work from 3.3 V at short distances, but a proper logic-level shifter gives the strip a cleaner 5 V data signal and improves margin, especially with longer wiring.
POWER
GPIO pins are signals, not power supplies.
Motors, servos, LED strips and other higher-current loads should use an appropriate external supply and driver rather than drawing their load current through an ESP32 pin. Connect grounds together when two powered circuits need a common signal reference, unless the design intentionally uses galvanic isolation.
Before powering a new build, check supply voltage, polarity, maximum current and connector pinout with a multimeter. The wiring builder can suggest a starting GPIO layout, but the component datasheet remains the final reference.