/* I2C slave Address Scanner
for 5V bus
 * Connect a 4.7k resistor between SDA and Vcc
 * Connect a 4.7k resistor between SCL and Vcc
for 3.3V bus
 * Connect a 2.4k resistor between SDA and Vcc
 * Connect a 2.4k resistor between SCL and Vcc

 */
#include <ESP8266WiFi.h>
#include <Wire.h>

void scan(){
Serial.println(" Scanning I2C Addresses");
uint8_t cnt=0;
for(uint8_t i=0;i<128;i++){
  Wire.beginTransmission(i);
  uint8_t ec=Wire.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.");
}

bool i2cReady(uint8_t adr){
uint32_t timeout=millis();
bool ready=false;
while((millis()-timeout<100)&&(!ready)){
  Wire.beginTransmission(adr);
  ready=(Wire.endTransmission()==0);
  }
return ready;
}

void eepromSize(){
Serial.println("Discovering eeprom sizes 0x50..0x57");
uint8_t adr=0x64,i;
uint16_t size;
char buf[64];
while(adr<0x58){
  i=0;
  size = 0x1000; // Start at 4k
  i += sprintf_P(&buf[i],PSTR("0x%02X: "),adr);
  if(i2cReady(adr)) { // EEPROM answered
    uint8_t zeroByte;
    Wire.beginTransmission(adr);
    Wire.write((uint8_t)0); // set address ptr to 0, two bytes High
    Wire.write((uint8_t)0); // set address ptr to 0, two bytes Low
    uint8_t err=Wire.endTransmission();
    if(err==0){// worked
      err=Wire.requestFrom(adr,(uint8_t)1);
      if(err==1){// got the value of the byte at address 0
        zeroByte=Wire.read();
        uint8_t saveByte,testByte;
        do{
          if(i2cReady(adr)){
            Wire.beginTransmission(adr);
            Wire.write(highByte(size)); // set next test address
            Wire.write(lowByte(size));
            Wire.endTransmission();
            err=Wire.requestFrom(adr,(uint8_t)1);
            if(err==1){
              saveByte=Wire.read();
              Wire.beginTransmission(adr);
              Wire.write(highByte(size)); // set next test address
              Wire.write(lowByte(size));
              Wire.write((uint8_t)~zeroByte); // change it
              err=Wire.endTransmission();
              if(err==0){ // changed it
                if(!i2cReady(adr)){
                  i+=sprintf_P(&buf[i],PSTR(" notReady2.\n"));
                  Serial.print(buf);
                  adr++;
                  break;
                  }
                Wire.beginTransmission(adr);
                Wire.write((uint8_t)0); // address 0 byte High
                Wire.write((uint8_t)0); // address 0 byte Low
                err=Wire.endTransmission();
                if(err==0){
                  err=Wire.requestFrom(adr,(uint8_t)1);
                  if(err==1){ // now compare it
                    testByte=Wire.read();
                    }
                  else {
                    testByte=~zeroByte; // error out
                    }
                  }
                else {
                  testByte=~zeroByte;
                  }
                }
              else {
                testByte = ~zeroByte;
                }
              //restore byte
              if(!i2cReady(adr)){
                i+=sprintf_P(&buf[i],PSTR(" notReady4.\n"));
                Serial.print(buf);
                adr++;
                break;
                }
              
              Wire.beginTransmission(adr);
              Wire.write(highByte(size)); // set next test address
              Wire.write(lowByte(size));
              Wire.write((uint8_t)saveByte); // restore it
              Wire.endTransmission();
              }
            else testByte=~zeroByte;
            }
          else testByte=~zeroByte;
          if(testByte==zeroByte){
            size = size <<1;
            }
          }while((testByte==zeroByte)&&(size>0));
        if(size==0) i += sprintf_P(&buf[i],PSTR("64k Bytes"));
        else i+=sprintf_P(&buf[i],PSTR("%dk Bytes"),size/1024);
        if(!i2cReady(adr)){
          i+=sprintf_P(&buf[i],PSTR(" notReady3.\n"));
          Serial.print(buf);
          adr++;
          continue;
          }
        Wire.beginTransmission(adr);
        Wire.write((uint8_t)0); // set address ptr to 0, two bytes High
        Wire.write((uint8_t)0); // set address ptr to 0, two bytes Low
        Wire.write(zeroByte);  //Restore
        err=Wire.endTransmission();
        }
      else i+=sprintf_P(&buf[i],PSTR("Read 0 Failure"));
      }
    else i+=sprintf_P(&buf[i],PSTR("Write Adr 0 Failure"));
      
    }
  else i+=sprintf_P(&buf[i],PSTR("Not Present."));
  Serial.println(buf);
  adr++;
  }
}

void setup(){
Serial.begin(115200);
 Wire.begin(D6, D5);                                 // I2C-Bus initialisieren GPIO2-Data GPIO0-Clock
 Wire.setClock(1000); 
scan();
Serial.println();
eepromSize();
}

void loop(){}