ESP32 Cheatsheet

The ESP32 is a low-cost microcontroller with integrated Wi-Fi and Bluetooth connectivity, ideal for IoT, control, and automation projects.

Initial Setup

Install the ESP32 Board in the Arduino IDE

To start programming the ESP32 with the Arduino IDE, you first need to add the board support.

https://dl.espressif.com/dl/package_esp32_index.json

Select the Board and Port

Once the board is installed, select the model of ESP32 you are using.

Tools > Board > ESP32 Dev Module

Select the USB port to which the ESP32 is connected:

Tools > Port > (Select the correct port)

First Program (Blink)

Code to blink an LED on the ESP32

void setup() {
  pinMode(2, OUTPUT);  // Set GPIO 2 as output
}

void loop() {
  digitalWrite(2, HIGH);  // Turn on the LED
  delay(1000);            // Wait 1 second
  digitalWrite(2, LOW);   // Turn off the LED
  delay(1000);            // Wait 1 second
}

Peripheral Management

GPIO (Digital Input and Output)

Configure a pin as input or output

pinMode(pin, OUTPUT);  // Set a pin as output
pinMode(pin, INPUT);   // Set a pin as input
digitalWrite(pin, HIGH);  // Set the pin value to HIGH or LOW
int state = digitalRead(pin);  // Read the state of a pin

PWM (Pulse Width Modulation)

Generate PWM signal on ESP32

const int ledPin = 2;
const int frequency = 5000;
const int pwmChannel = 0;
const int resolution = 8;
int dutyCycle = 128;  // 50% duty cycle

void setup() {
  ledcSetup(pwmChannel, frequency, resolution);
  ledcAttachPin(ledPin, pwmChannel);
}

void loop() {
  ledcWrite(pwmChannel, dutyCycle);  // Adjust the PWM duty cycle
}

ADC (Analog-to-Digital Converter)

Read an analog signal on ESP32

int value = analogRead(34);  // Read a value from ADC pin 34
Serial.println(value);

I2C

Configure I2C on ESP32

#include <Wire.h>

void setup() {
  Wire.begin(21, 22);  // SDA on pin 21, SCL on pin 22
}

void loop() {
  Wire.beginTransmission(0x3C);  // Start communication with device at address 0x3C
  Wire.write(0x00);  // Send data
  Wire.endTransmission();
}

Wi-Fi Connectivity

Connect to a Wi-Fi Network

Code to connect the ESP32 to a Wi-Fi network

#include <WiFi.h>

const char* ssid = "network_name";
const char* password = "password";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting...");
  }

  Serial.println("Connected to Wi-Fi");
}

void loop() {
  // Main code
}

Create an Access Point (AP)

Code to set up the ESP32 as a Wi-Fi access point

#include <WiFi.h>

void setup() {
  WiFi.softAP("ESP32_AP", "AP_password");

  Serial.begin(115200);
  Serial.println("Access point configured.");
}

void loop() {
  // Application logic
}

Bluetooth on ESP32

Classic Bluetooth

Enable Classic Bluetooth and pairing

#include "BluetoothSerial.h"

BluetoothSerial SerialBT;

void setup() {
  Serial.begin(115200);
  SerialBT.begin("ESP32test");  // Bluetooth device name
  Serial.println("Bluetooth ready to pair");
}

void loop() {
  if (SerialBT.available()) {
    char incomingChar = SerialBT.read();
    Serial.write(incomingChar);  // Display received data via Bluetooth
  }
}

Bluetooth Low Energy (BLE)

Set up the ESP32 as a BLE server

#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

void setup() {
  BLEDevice::init("ESP32_BLE");
  BLEServer *pServer = BLEDevice::createServer();
}

void loop() {
  // Logic for BLE communication
}

Power Management

Low Power Modes

Set the ESP32 in deep sleep mode

void setup() {
  esp_sleep_enable_timer_wakeup(10 * 1000000);  // Wake up in 10 seconds
  esp_deep_sleep_start();  // Enter deep sleep mode
}

void loop() {
  // Not executed in deep sleep
}

OTA (Over-the-Air Update)

Upload Code via Wi-Fi

Set up OTA on the ESP32

#include <WiFi.h>
#include <ArduinoOTA.h>

void setup() {
  WiFi.begin("network_name", "password");
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }

  ArduinoOTA.begin();
}

void loop() {
  ArduinoOTA.handle();  // Process OTA update requests
}