ESP32

Learn

What you’ll learn

• What makes the ESP32 different from an Arduino UNO
• How to program it in the Arduino IDE or MicroPython
• The 3.3 V rule

The ESP32

	Arduino UNO R3	ESP32 (typical dev board)
Processor	8-bit, 16 MHz	32-bit, up to 240 MHz, often dual-core
Memory	2 KB RAM	Hundreds of KB of RAM
Wi-Fi / Bluetooth	No	Yes
Logic voltage	5 V	3.3 V
Price	~$20 (clones less)	~$5–10

Programming it

• Arduino IDE: install the esp32 boards package (Boards Manager), pick your board, and most Arduino code works.
• MicroPython: flash MicroPython firmware and write Python.

The 3.3 V rule

Don't feed 5 V into ESP32 pins

ESP32 GPIO pins are 3.3 V. A 5 V signal (for example the HC-SR04’s ECHO) can damage them. Use a voltage divider or a 3.3 V-compatible sensor.

Robot uses

• A web page or phone app to drive the robot over Wi-Fi
• Bluetooth gamepad control
• Sending sensor data to a laptop for logging

Examples

Example: a tiny Wi-Fi web server

#include <WiFi.h>
#include <WebServer.h>

WebServer server(80);

void setup() {
  Serial.begin(115200);
  WiFi.begin("your-network", "your-password");
  while (WiFi.status() != WL_CONNECTED) delay(200);
  Serial.println(WiFi.localIP());           // open this address in a browser
  server.on("/", [] { server.send(200, "text/html", "<h1>Hello from the robot</h1>"); });
  server.on("/go", [] { /* start motors */ server.send(200, "text/plain", "going"); });
  server.begin();
}

void loop() { server.handleClient(); }

Example: a 5 V sensor on a 3.3 V pin

HC-SR04 ECHO → 1 kΩ → ESP32 pin, and from the ESP32 pin → 2 kΩ → GND. This divider brings 5 V down to about 3.3 V.

Practice

Try it in a virtual ESP32

Press Start simulator and replace sketch.ino with this, then press ▶ and watch the Serial Monitor.

sketch.ino

void setup() {
  Serial.begin(115200);
  Serial.println("Hello from the ESP32!");
}

void loop() {
  Serial.print("Uptime (s): ");
  Serial.println(millis() / 1000);
  delay(1000);
}

Virtual ESP32Open full screen ↗

Start simulator

Runs on Wokwi, free, no account needed.

CompareEasy

List three advantages and one danger of the ESP32 compared with an UNO. Advantages: Wi-Fi/Bluetooth, much faster, more memory (also cheaper). Danger: 3.3 V pins can be damaged by 5 V signals.

Faster printsMedium

Print the uptime every 250 ms in milliseconds. Print millis() directly and use delay(250).

Divider for ECHOHard

Design a voltage divider to bring a 5 V ECHO signal to at most 3.3 V. 1 kΩ on top, 2 kΩ to GND: 5 × 2/3 ≈ 3.33 V. (Or 10 kΩ / 20 kΩ.)

Quick check

1. What does an ESP32 have that an UNO R3 doesn’t?

USBWi-Fi and BluetoothPinsA reset button

2. ESP32 GPIO logic level is…

5 V3.3 V12 V1.5 V

3. Can you program an ESP32 in the Arduino IDE?

NoYes, after installing the esp32 boards packageOnly in blocksOnly with a special cable

Check my answers