I2C Voltage for Arduino MKR Zero

Hello, I have recently been looking into the Arduino MKR Zero for a project.

It fulfills all of my requirements (microSD, I2C, JST LiPo Connector, ...) except I can't find the I2C logic voltage. I know the board runs on 3.3 V, and the pins are all 3.3V, however I am confused by the additional I2C connector which has a 5V rail.

Does this mean I2C is also running on 5V? Can the rail be set to 3.3V for 3.3V sensors?

Thanks.

No and no but there is a 3V3 rail available. The 5 volts is there because that is the supply voltage and it is usually needed by something you'll be connecting. But, all I/O pins are 3V3 only which includes the pins used for I2C. So, to use a 5V I2C device, you'll need one of the bidirectional level translators.

Also be aware that in addition to 3V3 I/O, ARM processors have lower port output current capabilities, only 7ma for the SAMD21.