esp32-scan-i2c.cpp

#include <Arduino.h>
#include <Wire.h>

// Elechouse PN532 v3 board 
// Switch: 1, 0 for I2C

#define SDA1 21
#define SCL1 22

TwoWire I2Cone = TwoWire(0);

void scan1(){
Serial.println("Scanning I2C Addresses");
uint8_t cnt=0;
for(uint8_t i=0;i<128;i++){
  I2Cone.beginTransmission(i);
  uint8_t ec=I2Cone.endTransmission(true);
  if(ec==0){
    if(i<16)Serial.print('0');
    Serial.print(i,HEX);
    cnt++;
  }
  else Serial.print("..");
  Serial.print(' ');
  if ((i&0x0f)==0x0f)Serial.println();
  }
Serial.print("Scan Completed, ");
Serial.print(cnt);
Serial.println(" I2C Devices found.");

}

void setup() {
  Serial.begin(115200);
  I2Cone.begin(SDA1,SCL1,400000); // SDA pin 21, SCL pin 22
}

void loop() {
  scan1();
  Serial.println(); 
  delay(100);
}