Texas Instruments MSP430x1xx manual 2. Up Mode

Timer_A Operation

Up Mode

The up mode is used if the timer period must be different from 0FFFFh counts. The timer repeatedly counts up to the value of compare register TACCR0, which defines the period, as shown in Figure 11−2. The number of timer counts in the period is TACCR0+1. When the timer value equals TACCR0 the timer restarts counting from zero. If up mode is selected when the timer value is greater than TACCR0, the timer immediately restarts counting from zero.

Figure 11−2. Up Mode

0FFFFh

TACCR0

0h

The TACCR0 CCIFG interrupt flag is set when the timer counts to the TACCR0 value. The TAIFG interrupt flag is set when the timer counts from TACCR0 to zero. Figure 11−3 shows the flag set cycle.

Figure 11−3. Up Mode Flag Setting

Timer Clock

Timer CCR0−1 CCR0 0h 1h CCR0−1 CCR0 0h

Set TAIFG

Set TACCR0 CCIFG

Changing the Period Register TACCR0

When changing TACCR0 while the timer is running, if the new period is greater than or equal to the old period, or greater than the current count value, the timer counts up to the new period. If the new period is less than the current count value, the timer rolls to zero. However, one additional count may occur before the counter rolls to zero.

11-6Timer_A