Finding I2C devices on an ESP32 is a great way to identify and troubleshoot connected peripherals. The I2C scanner is a sketch (program) that scans the I2C bus to detect devices. Here’s how you can find and use an I2C scanner on an ESP32:

Steps to Find and Use an I2C Scanner on ESP32

. Open the I2C Scanner Sketch

• Open the Arduino IDE.
• Go to File > Examples > Wire > Scanner. This will open a sketch for scanning I2C devices.

Modify the Sketch for ESP32

The I2C scanner sketch should work out of the box for most boards, including the ESP32, but it’s a good idea to ensure you have the correct configuration. The default sketch should be fine, but here’s a basic version you can use:

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin();
  Serial.println("\nI2C Scanner");
}

void loop() {
  byte error, address;
  int nDevices = 0;

  Serial.println("Scanning...");

  for (address = 1; address < 127; address++) {
    // The address of an I2C device can be from 1 to 127
    Wire.beginTransmission(address);
    error = Wire.endTransmission();

    if (error == 0) {
      Serial.print("I2C device found at address 0x");
      if (address < 16) {
        Serial.print("0");
      }
      Serial.print(address, HEX);
      Serial.println(" !");

      nDevices++;
    }
    else if (error == 4) {
      Serial.print("Unknown error at address 0x");
      if (address < 16) {
        Serial.print("0");
      }
      Serial.println(address, HEX);
    }
  }

  if (nDevices == 0) {
    Serial.println("No I2C devices found.");
  }
  else {
    Serial.println("Done.");
  }

  delay(5000); // Wait 5 seconds before the next scan
}

Upload the Sketch

• Connect your ESP32 to your computer via USB.
• Select the correct board and port in the Arduino IDE:
  • Go to Tools > Board and select your ESP32 board (e.g., ESP32 Dev Module).
  • Go to Tools > Port and select the correct port.
• Click the upload button (right arrow icon) to upload the sketch to your ESP32.

Open the Serial Monitor

• Once the upload is complete, open the Serial Monitor:
  • Go to Tools > Serial Monitor or press Ctrl+Shift+M (or Cmd+Shift+M on macOS).
  • Set the baud rate to 115200.

View the Results

• The Serial Monitor will display the addresses of any I2C devices connected to your ESP32.
• It will show something like

I2C Scanner
Scanning...
I2C device found at address 0x3C !
I2C device found at address 0x27 !
Done.