CCS/MSP430F5438A: Difficulty with Timer A - Capture mode

The best way to go about resolving this kind of problems is to use break points in CCS and literally use wires (maybe with an RC at the input to smooth the transition) to create a rising or a falling edge. I would recommend that you first confirm the interrupt triggers at the rising edge. Then, confirm it triggers at the falling edge. If your code can do this with a very slow signal, then there is no reason why it wouldn't with the PWMed signal (given the PMWed signal is slower compared to the frequency of the MCU).

I have used breakpoints and debugger but my code is never coming from the interrupt, and I don't understand why, because the sensor is working on 1-4 kHz, and my timer has a much faster frequency - SMCLK. I give you my code to glance at it and tell me if you see any illogical part... The code for the LCD is working properly, so you don't have to check that.

#include <msp430.h>
#include <stdio.h>
#include <stdlib.h>

// uC Port definitions
#define lcd_port P8OUT
#define lcd_port_dir P8DIR

// LCD Registers masks based on pin to which it is connected
#define LCD_EN BIT3
#define LCD_RS BIT2

#define title1 "Temperature:"
#define title2 "Out of range!"

/*SMT 16030 temperature sensor
DC=0.320+0.00470*t ( t = degrees C)
DC is in range from 0,1 to 1
t=(DC-0.320)/0.00470
For 0,1 t=-46
For 1 t=144
*/

unsigned long int result = 0; //temperature in degrees C
unsigned long int pom = 0;
unsigned long int temp = 0;
unsigned long int duty = 0;
unsigned int pp_done = 0;
unsigned int np_done = 0;
char buffer[20];
char n[4];
unsigned long int count_pp_1=0;
unsigned long int count_np_1=0;

void lcd_reset()
{
lcd_port_dir = 0xff; // output mode
lcd_port = 0xff;
__delay_cycles(20000);
lcd_port = 0x30+LCD_EN;
lcd_port = 0x30;
__delay_cycles(10000);
lcd_port = 0x30+LCD_EN;
lcd_port = 0x30;
__delay_cycles(1000);
lcd_port = 0x30+LCD_EN;
lcd_port = 0x30;
__delay_cycles(1000);
lcd_port = 0x20+LCD_EN;
lcd_port = 0x20;
__delay_cycles(1000);
}

void lcd_cmd (char cmd)
{
// Send upper nibble
lcd_port = (cmd & 0xF0)|LCD_EN;
lcd_port = (cmd & 0xF0);

// Send lower nibble
lcd_port = ((cmd << 4) & 0xF0)|LCD_EN;
lcd_port = ((cmd << 4) & 0xF0);

__delay_cycles(4000);
}

void lcd_init ()
{
lcd_reset(); // Call LCD reset
lcd_cmd(0x28); // 4-bit mode - 2 line - 5x7 font.
lcd_cmd(0x0C); // Display no cursor - no blink.
lcd_cmd(0x06); // Automatic Increment - No Display shift.
lcd_cmd(0x80); // Address DDRAM with 0 offset 80h.
lcd_cmd(0x01); // Clear screen
}


void lcd_data (unsigned char dat)
{
// Send upper nibble
lcd_port = ((dat & 0xF0)|LCD_EN|LCD_RS);
lcd_port = ((dat & 0xF0)|LCD_RS);

// Send lower nibble
lcd_port = (((dat << 4) & 0xF0)|LCD_EN|LCD_RS);
lcd_port = (((dat << 4) & 0xF0)|LCD_RS);

__delay_cycles(4000); // a small delay may result in missing char display
}

void display_line(char *line)
{
while (*line)
lcd_data(*line++);
}

/**
* main.c
*/
int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // stop watchdog timer

// Initialize LCD
lcd_init();
// Writing on the LCD
lcd_cmd(0x80); // select 1st line (0x80 + addr) - here addr = 0x00
display_line(title1);

// Setup PWM sensor
P8SEL |= BIT0; // Select port P8.0 for TA0
P8DIR &= ~BIT0; // Configure P8.0 as input

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

TA0CCTL0 = CCIE | CM_1 | SCS | CAP | CCIS_1; // CCR0, capture on rising edge
int i;

__enable_interrupt(); // GIE

while (1) {
if(np_done) {

duty = 10000 * (count_pp_1 / (count_pp_1 + count_np_1));
result = (duty - 3200) / 47;


if ((result <= 100) && (result >= 0)) { //software debouncing
temp = result;
for (i = 3; i >= 0; i--) {
n[i] = ((temp % 10) + '0');
temp /= 10;
}

lcd_cmd(0xc0);
display_line(niz);
}
else {
lcd_cmd(0xc0);
display_line(title2);
}

__delay_cycles(4000);


count_pp_1 = 0;
count_np_1 = 0;
pp_zavrseno = 0;
np_zavrseno = 0;

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

//Next CCP0 interrupt one rising edge
TA0CCTL0 &= ~CM1;
TA0CCTL0 |= CM0;
TA0CCTL0 |= CCIE;
TA0CCTL0 &= ~CCIFG;

}
}

return 0;
}

void __attribute__ ((interrupt(TIMER0_A0_VECTOR))) timerA0Isr(void)
{
if (TA0CCTL0 & CCIFG) { //CCP0 interrupt

if ((TA0CCTL0 & CM_1) && (pp_done == 0)) { //rising edge

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

TA0CCTL0 &= ~CM0;
TA0CCTL0 |= CM1; //Set CCP0 module interrupt on the falling edge
TA0CCTL0 &= ~CCIFG; // Reset the interrupt flag

}

else if((TA0CCTL0 & CM_2) && (pp_done == 0)) { //falling edge

count_pp_1 = TA0CCR0; // TA0R

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

TA0CCTL0 &= ~CM0;
TA0CCTL0 |= CM1; //Set CCP0 module interrupt on the falling edge
TA0CCTL0 &= ~CCIFG; // Reset the interrupt flag

pp_done = 1;
}

else if((TA0CCTL0 & CM_2) && (pp_done == 1) && (np_done == 0)) {

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

TA0CCTL0 &= ~CM1;
TA0CCTL0 |= CM0; //Set CCP0 module interrupt on the rising edge
TA0CCTL0 &= ~CCIFG; // Reset the interrupt flag

}

else if((TA0CCTL0 & CM_1) && (pp_done == 1) && (np_done == 0)) {

count_np_1 = TA0CCR0; // TA0R

TA0CTL = TACLR; // Setting this bit clears TAR, the clock divider logic, and the count direction
TA0CTL = TASSEL__SMCLK | MC_2; // ACLK, mode control: continual

TA0CCTL0 &= ~CCIFG; // Reset the interrupt flag
TA0CCTL0 &= ~CCIE; // Disable CCP0 interapt

np_done = 1;// finished
}
}
}