SLAZ508AC January 2013 – May 2021 MSP430F67681
USCI Module
Functional
UCLKI not usable in I2C master mode
When EUSCIB is configured as I2C Master with the external UCLKI as clock source, the UCLKI signal is not available and cannot be used to source I2C clock.
Use LFXTCLK via ACLK or HFXTCLK via SMCLK as clock source (BRCLK) for I2C in master mode with external clock source.