MSP430FR5994: Calculation of time

Hi Gaosheng,

Unfortunately, there is no "built-in" feature or function in the MSP430FR5994 MCU.  However, this could be done easily in SW using any of it's multiple timers.

Here [link] is a very simple example showing how you might use a timer.  I modified it a little here to show you how to use the interrupt to update a counter once every second.  It will even toggle an IO pin, if you want, so you can monitor with an oscilloscope or logic probe.

If you want a different update rate, change the period of the timer TA0CCR0 register value.  For example if you want to count the number of 0.1 seconds, then change TA0CCR0 value to (32768/10). 

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;               // Stop WDT

    // Configure GPIO
    P1DIR |= BIT0;
    P1OUT |= BIT0;

    // Disable the GPIO power-on default high-impedance mode to activate
    // previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;
    
    long seconds_counter = 0;

    TA0CCTL0 = CCIE;                        // TACCR0 interrupt enabled
    TA0CCR0 = 32768;                        // Using ACLK @ 32768KHz, generate interrupt every 1 second
    TA0CTL = TASSEL__ACLK | MC__UP;        // ACLK, UP mode

    __bis_SR_register(LPM0_bits + GIE);     // Enter LPM0 w/ interrupt
    __no_operation();                       // For debugger
}

// Timer0_A0 interrupt service routine
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = TIMER0_A0_VECTOR
__interrupt void Timer0_A0_ISR (void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(TIMER0_A0_VECTOR))) Timer0_A0_ISR (void)
#else
#error Compiler not supported!
#endif
{
    P1OUT ^= BIT0;
    seconds_counter++;
}

Does this help answer your question?