Other Parts Discussed in Thread: MSP-EXP430FR5994
Tool/software: Code Composer Studio
I am trying to get a simple Timer A0 ISR to fire every 2 ms using the DCO clock. I run into two problems when I debug this in CCSv8. First, single stepping the code after the interrupt condition has been met (TA0CCTL0.CCIFG = 1 and TA0CTL.TAIFG = 1) never sends execution into the ISR even with the GIE =1. But when I allow the code to run from this point, it enters the isr_trap.asm routine, which would seem to indicate there is something wrong with the ISR vectoring. Since I cannot reproduce the vectoring into the isr_trap.asm by single stepping, I'm stuck. Any clues for the source of these problems (they are probably related) would be welcome. Thx! Code is below, and I am using the MSP-EXP430FR5994 LaunchPad.
// Project Name: TA0InterruptTest
#include <msp430.h>
/* GLOBAL VARIABLE AND CONSTANT INITIALIZATION */
static unsigned int count = 0; // counter for ISR loops
/* FUNCTION DEFINTIONS */
/* Initialize GPIO */
void Init_GPIO(void)
{
// initialize port bits on the LaunchPad board
P1DIR |= BIT1 | BIT0; // setup P1.0 and P1.1 as outputs for the on board red and green LEDs
P1OUT &= ~(BIT1 | BIT0); // start with both LEDs off
P4DIR |= BIT1; // setup P4.1 as diagnostic bit for ISR from TA0
PM5CTL0 &= ~LOCKLPM5; // clear the LPM5 lock bit to release I/O pins from high-Z state
}
/* Initialize Clock System */
void Init_Clock(void)
{
CSCTL0_H = CSKEY_H; // unlock CS registers by writing password 0xA5 to upper byte
CSCTL1 = DCOFSEL_0; // set DCORSEL = 0, DCOFSEL = 000b, for 1 MHz output (approximately)
CSCTL2 = SELA__VLOCLK | SELS__DCOCLK | SELM__DCOCLK; // set ACLK = VLOCLK, SMCLK = DCOCLK, and MCLK = DCOCLK
CSCTL0_H = 0; // relock CS registers by writing incorrect password (zero)
}
/* Timer TAO Initialization */
void Init_TA0(void)
{
TA0CCR0 = 2000-1; // set period to 2000 counts: 2.00 ms period, 500 Hz
TA0CCTL0 = CCIE; // set interrupt enable for TA0CCR0
TA0CTL = TASSEL__SMCLK | MC__UP | TACLR | TAIE; // set source to SMCLK, count up, initially clear the TCR, enable interrupt
}
/* Timer TA0 ISR */
#pragma vector = TIMER0_A0_VECTOR
__interrupt void Timer0_A0_ISR (void) // timer TA0 fires every 2.00 ms; ISR triggers at a 500 Hz rate
{
P4OUT ^= BIT1; // toggle P4.1; this should produce a 250 Hz square wave diagnostic output for scope triggering
count++; // increment loop counter
if(count == 500) // should occur with a period of 500 x 2.0 ms = 1.000 second (1.00 Hz)
{
P1OUT ^= BIT1; // toggle P1.1 green LED
count = 0; // reset counter
}
}
/* MAIN PROGRAM BODY */
/* main.c */
int main(void)
{
/* HARDWARE INITIALIZATION */
WDTCTL = WDTPW | WDTHOLD; // stop watchdog timer
Init_GPIO(); // initialize the GPIO pins
Init_Clock(); // initialize the Clock System
Init_TA0(); // initialize Timer TA0
__enable_interrupt(); // enable global interrupts
__no_operation(); //
/* MAIN LOOP */
while(1)
{
P1OUT ^= BIT0; // toggle P1.0 red LED
__delay_cycles(10000); // buy time
}
}
