13.22.6.2.4.1.2 Master Clock Generation (High-Speed Mode)

For I²C Hs transfers, there is no SCL synchronization. Instead, the SCL frequency is determined by the GCLK_SERCOMx_CORE frequency (f_GCLK) and the High-Speed Baud setting in the Baud register (BAUD.HSBAUD). When BAUD.HSBAUDLOW=0, the HSBAUD value will determine both SCL high and SCL low. In this case the following formula determines the SCL frequency.

$f_{SCL} = \frac{f_{GCLK}}{{2 + 2 \cdot H S B A U D}_{}}$

When HSBAUDLOW is non-zero, the following formula determines the SCL frequency.

$f_{SCL} = \frac{f_{GCLK}}{{2 + H S B A U D + H S B A U D L O W}_{}}$

Note: The I²C standard Hs (High-speed) requires a nominal high to low SCL ratio of 1:2, and HSBAUD should be set accordingly. At a minimum, BAUD.HSBAUD and/or BAUD.HSBAUDLOW must be non-zero.