I2C-Scanner für den ESP32; scannt beide Standardkanäle (I2C_1: SDA=GPIO 21, SCL=22; I2C_2: SDA=17, SCL=16) // leicht modifizierte Version des Codes von Kutscher07; https://github.com/espressif/arduino-esp32/issues/977#issuecomment-365734787

ESP32_I2C-Scanner_2_channels.ino

/* I2C address scanner
 
  Source: Kutscher07
  https://github.com/espressif/arduino-esp32/issues/977#issuecomment-365734787
 
  slightly modified version (only one scan function,
  passing the I2C channel as parameter)
 
  2020-11-19 Heiko / unsinnsbasis.de
*/
#include <Wire.h>
 
// I2C channel 1: SDA and SCL pin
#define SDA1 21
#define SCL1 22
// I2C channel 2: SDA and SCL pin
#define SDA2 17
#define SCL2 16
 
TwoWire I2Cone = TwoWire(0);
TwoWire I2Ctwo = TwoWire(1);
 
void scan(TwoWire * tw, char channel) {
  Serial.print("Scanning I2C addresses on channel ");
  Serial.println(channel);
  uint8_t cnt=0;
  for (uint8_t i=0; i<128; i++) {
    tw->beginTransmission(i);
    uint8_t ec = tw->endTransmission(true);
    if (ec == 0) {
      if (i<16) Serial.print('0');  // add leading zero
      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 device(s) found.");
  Serial.println();
}
 
void setup() {
  Serial.begin(115200);
  I2Cone.begin(SDA1, SCL1, 400000);
  I2Ctwo.begin(SDA2, SCL2, 400000);
}
 
void loop() {
  scan(&I2Cone, '1');
  delay(100);
  scan(&I2Ctwo, '2');
  delay(10000);
}