21.3.3.4 Synchronized with TCA0

The TCB can be configured to use the clock (CLK_TCA) of the Timer/Counter type A (TCA0) by writing 0x2 to the Clock Select bit field (CLKSEL) in the Control A register (TCB.CTRLA). In this setting the TCB will count either on the prescaled clock signal from TCA0 which is configured by CLKSEL in TCA.CTRLA, or event clocking for TCA configured by EVACT in TCA.EVCTRL. Event clocking from TCA0 is only used if enable count on event (CNTEI) is set to '1' in TCA.EVCTRL.

When the Synchronize Update bit (SYNCUPD) in the Control A register (TCB.CTRLA) is written to '1', the TCB counter will restart when the TCA0 counter restarts.