SLAZ220P October 2012 – May 2021 MSP430F46171
TB Module
Functional
Interrupt is lost (slow ACLK)
Timer_B counter is running with slow clock (external TBCLK or ACLK) compared to MCLK. The compare mode is selected for the capture/compare channel and the CCRx register is incremented by 1 with the occurring compare interrupt (if TBR = CCRx).
Due to the fast MCLK, the CCRx register increment (CCRx = CCRx + 1) happens before the Timer_B counter has incremented again. Therefore, the next compare interrupt should happen at once with the next Timer_B counter increment (if TBR = CCRx + 1). This interrupt is lost.
Switch capture/compare mode to capture mode before the CCRx register increment. Switch back to compare mode afterward.