Hi all,
I'm developing an application to understand how to manage global variable, loops and interrupts.
I post a little piece of code, to keep it simple:
volatile unsigned int test = 0;
int main( void )
{
volatile unsigned int i;
int result;
// stop watchdog timer to prevent time out reset
WDTCTL = WDTPW + WDTHOLD;
// init mcu ports
init_ports();
// dco calibration
for( i = 0; i < 0xFFFF; i++){} // delay for ACLK startup
result = TI_SetDCO(TI_DCO_4MHZ);
if( result == TI_DCO_SET_TO_SLOWEST ) // returned result if DCO registers hit min
{
while(1); // trap the CPU if hit
}
else if( result == TI_DCO_SET_TO_FASTEST )// returned result if DCO registers hit max
{
while(1); // trap the CPU if hit
}
else if( result == TI_DCO_TIMEOUT_ERROR ) // returned result if DCO takes >10000 loops
{
while(1); // trap the CPU if hit
}
// smclk = mclk / 4
BCSCTL2 = SELM0 | DIVS1;
// set test global variable to 0
test = 0;
// led0 on
P5OUT &= ~(0x01 << 4);
// configure timer
TAR = 0;
CCTL0 = CCIE;
CCR0 = 32768;
// start timer
TACTL = TASSEL_1 | MC_1;
// lpm0 + gie
_BIS_SR(LPM0_bits + GIE);
// while loop
while(test < 2);
// stop timer
TACTL &= ~MC_1;
// led1 on
P5OUT &= ~(0x01 << 5);
return 0;
}
#pragma vector=TIMERA0_VECTOR
__interrupt void TimerA0_ISR (void)
{
// increment test global variable
test++;
// led2 toggle
P5OUT ^= (0x01 << 6);
}
The behaviour I was expecting from this software was: led0 on, led2 toggle 2 times and the variable test should be = 2, then the while loop on main should break and timer be stopped and led1 turned on.
The behaviour I'm seeing is: led0 on, led2 toggle forever and led 1 never turns on.
It seems that the while loop in main is looping indefinitely and I can't understand what is wrong.
Thanks for your support.
Regards,
Samuele.
