Honored Contributor
Honored ContributorYou shouldn't need a different phase clock. The clock from the crystal is the reference and will be used to drive the SDA and SCL signals. In I2C the SCL isn't a free running clock and you can control its level based on your reference clock.
For example, let's suppose that the crystal clock is 200KHz. If you toggle the SCL signal (scl <= not scl) at every rising edge of the crystal clock, the SCL would be a 100KHz clock. Since your module is using the 200KHz as reference it is now possible to control the SDA signal between each edge of the SCL.
