Other Parts Discussed in Thread: MSP430FR2311, MSP430WARE
Tool/software: Code Composer Studio
Following is the program designed to generate a PWM pattern using MSP430FR2000. I am operating the processor at 16 MHz. The timer 0 sourced by SMCLK, working in continuous mode outputs PWM at P2.0. The TBxCCR1 bits are continuously varied to generate different frequencies, starting from 8 KHz. However at the beginning for a time period of 660ms , the frequency produced is very low which begins at 100 Hz . The same code tested on MSP430FR2311 launch pad does not show this unusual behaviour. Please let me know what could be the reason for this.
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR = BIT0 ; //Set 1.0 to output
P1SEL1 = BIT0 ; // Select the function required for 1.0 .Secondary function is selected here.
P2DIR = BIT0;
P2SEL0 = BIT0 ;
CSCTL1 = DCORSEL_5; // DCO frequency select
CSCTL2 = FLLD_0; // FLL loop divider
PM5CTL0 &= ~LOCKLPM5;
TB0CCTL1 = OUTMOD_4 | CCIE; // TACCR1 toggle, interrupt enabled
TB0CTL = TBSSEL_2 | MC_2| CNTL_0| TBIE | ID_0 |TBCLR ; // SMCLK, Cont mode, int enabled
__bis_SR_register(GIE);
}
#pragma vector=TIMER0_B1_VECTOR
__interrupt void Timer_B1(void)
{
volatile unsigned int x=0;
volatile unsigned int y=0;
volatile unsigned int m=0;
x=BAKMEM0;
y=BAKMEM1;
m=BAKMEM2;
switch( TB0IV )
{
case 2: y++;
// P1OUT ^= 0x04;
if((m%2)==0)
{
if((y%2)==0)
{
x=x+0x40;
}
TB0CCR1 += 1000+x; // reload period
if(x>1200)
{
m++;
//P1OUT ^= 0x02;
}
}
if((m%2)!=0)
{
if((y%2)==0)
{
x=x-0x40;
}
TB0CCR1 += 1000+x; // reload period
if(x<80
)
{
m++;
x=0;
//P1OUT ^= 0x02;
}
}
BAKMEM0=x;
BAKMEM1=y;
BAKMEM2=m;
break;
case 10: P2OUT ^= 0x01; // Timer overflow
break;
default: break;
}
}
