ESP8266 Community Forum

Same answer as provided in the other thread :

Effectively, 0x50 is the I2C address of AT24Cxxx EEPROM, not the DS1307 which is supposed to be 0x68.
Since EEPROM has been found, you I2C bus is working, but DS1307 didn't responded, it is problably badly wired or defective. If you are using those small PCB having both EEPROM and DS1307 on the same board, you need to verify if those have separate I2C buses or not, if separate, you need to connect both of them.

PROBLEM SOLVED!!!
I put two 2k2 pull up (3.3V) resistor at the SDA and SCL pins.
And i used Wire.begin(4,5);
Thanks you very much.

Use 5 volt Logic converter. This is the only Solution to this problem.

You can find below example for 2 RTC IC's that are 3.3V tolerant and more than suitable for ESP8266:

- DS3231 module : Driver example and also example for the onboard AT24C32 EEPROM
- PCF8563 : Driver example