MicrocontrollersQUICK REFERENCE
ESP32
A functional GPIO map for the original ESP32-WROOM development boards.
01GPIO map
- General I/O
- Common choices: 18, 19, 21, 22, 23, 25, 26, 27, 32, 33. Verify board use.
- Input only
- GPIO34–39; no internal pull-up/down. 37/38 usually not exposed.
- Avoid
- GPIO6–11 connect to flash. 16/17 may be reserved for PSRAM on WROVER.
02Analog & buses
- ADC
- ADC1: GPIO32–39. Prefer ADC1 when using Wi-Fi; ADC2 is shared with Wi-Fi.
- DAC / PWM
- 8-bit DAC on 25/26; LEDC PWM on output-capable GPIOs. ADC range depends on attenuation.
- I2C example
- SDA 21 / SCL 22; configurable in software.
- SPI / UART
- SPI example: MOSI 23, MISO 19, SCK 18, CS 5. UART0 TX 1 / RX 3; often used by USB.
03Boot rules
- Strapping
- GPIO0, 2, 5, 12, 15 are sampled at reset. Attached circuits must preserve required boot levels.
- Power
- Use board USB/VIN as documented. GPIOs are 3.3 V only.
- Variants
- ESP32-S2/S3/C3 have different pin maps and peripheral availability.