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

unsigned long lastScan = 0;
unsigned long sequence = 0;

void scan() {
  Wire.beginTransmission(0x68);
  int first = Wire.endTransmission();
  Wire.beginTransmission(0x69);
  int second = Wire.endTransmission();
  sequence++;
  Serial.printf("SCAN seq=%lu addr_0x68=%s(%d) addr_0x69=%s(%d) t_ms=%lu\n",
    sequence, first == 0 ? "ACK" : "NACK", first,
    second == 0 ? "ACK" : "NACK", second, millis());
}

void setup() {
  Serial.begin(115200);
  Wire.begin(21,22);
  Serial.println("I2C ADDRESS LAB READY; SDA=21 SCL=22, MPU6050 AD0 selects address");
  Serial.println("Probe 0x68 then 0x69; code 0=ACK, code 2=NACK");
  scan();
}

void loop() {
  if (millis() - lastScan >= 1200) {
    lastScan = millis();
    scan();
  }
  delay(10);
}