说明：  Description: Toggle P1.0 using software and Timer_A overflow ISR. // In this example an ISR triggers when TA overflows. Inside the TA // overflow ISR P1.0 is toggled. Toggle rate is approximatlely 12Hz. // Proper use of the TAIV interrupt vector generator is demonstrated. // ACLK = n/a, MCLK = SMCLK = TACLK = default DCO ~800kHz