ESP32 essentials · Lesson
10 min read
Meet the ESP32
A 240 MHz dual-core board with Wi-Fi and Bluetooth — and 3.3 V pins.
What You Will Learn
- Compare the ESP32 with the Uno
- Know the 3.3 V rule
- Find pins to avoid
| Arduino Uno | ESP32 DevKit V1 | |
|---|---|---|
| CPU | 8-bit, 16 MHz | 32-bit dual-core, up to 240 MHz |
| RAM | 2 KB | 520 KB |
| Logic level | 5 V | 3.3 V (not 5 V tolerant) |
| ADC | 10-bit, 6 pins | 12-bit, up to 18 channels |
| Wireless | — | Wi-Fi + Bluetooth |
ESP32 pins are 3.3 V only. Putting 5 V on a GPIO (for example from an HC-SR04 echo) can permanently damage the chip.
Highlighted Pins on esp32-devkit-v1GPIO2, GPIO34, GPIO25, GPIO21, GPIO22
GPIO2: on-board LED. GPIO34–39: input-only. GPIO25/26: DAC. GPIO21/22: I²C.
- GPIO6–11 connect to the flash chip and aren't on this board's headers — never use them.
- GPIO0, 2, 5, 12 and 15 are strapping pins: they decide how the chip boots. Avoid pulling them at power-up.
- ADC2 pins stop working while Wi-Fi is on; use ADC1 (GPIO32–39) for sensors in Wi-Fi projects.
ESP32: blink the on-board LEDesp32-devkit-v1
Check Your Understanding
Test what you learned in this lesson