5V Clock module with arduino DUE

hey guys.
hope you can help me out. We tried to switched from UNO to DUE due to performance issues and now we try to get the old clock module (5V exactly this one, http://bildr.org/2011/03/ds1307-arduino/) working on the DUE.

I've found the to possible SCL / SDA Ports and tried both.
I've also tried 5V and 3.3V.

Do I have to power the module with 5V and use resistors? Or can I also use 3.3V with this Module?

Thanks for helping me out in this one,
kind regards, tobi

slash:
hey guys.
hope you can help me out. We tried to switched from UNO to DUE due to performance issues and now we try to get the old clock module (5V exactly this one, http://bildr.org/2011/03/ds1307-arduino/) working on the DUE.

I've found the to possible SCL / SDA Ports and tried both.
I've also tried 5V and 3.3V.

Do I have to power the module with 5V and use resistors? Or can I also use 3.3V with this Module?

Thanks for helping me out in this one,
kind regards, tobi

The DS1307 would not work with 3.3V and the TWI Signals need an Levelshift from 5V to 3.3V.

5V would damage the DUE

If i'm right:
SDA and SCL (Pins 20&21) have Pullups --> TWI0
SDA1 and SCL1 (after Pin13) doesn't have Pullups --> TWI1

Btw. if you have an Due with RTC crystal (between the LED line RX,TX,L,ON and the chip, near the chip) you can use the internal clock.