Real Time Clock Issue

[Tokn59]

Hello, I am trying to integrate a RTC module (DS3231). It works fine as long as I don't use the M5Stack library. As soon as I combine M5.begin() with Wire.begin() there seems to be a conflict. Scanning I2C reveals 2 devices :

0x57 - M5 LCD ?
0x68 - RTC Module DS3231

Any clue as to what is going wrong ? What PINS are used by the LCD ? I suppose 21 (SDA) and 18 (SCL) ?

Kind Regards,

Tony