MSP432 P3.3 IRQ when NOT debugging

Chester Gillon said:

Therefore, it appears that the act of the program entering LPM4.5 when the debugger is not attached caused the P1.0 output not to toggle for some reason.

As the code doesn't clear the LOCKLPM5 bit , when the code wakes from LPM4.5 the code is unable to control the I/O pins.

With the code modified to clear the LOCKLPM5 bit upon waking-up from LPM4.5 then when run without the debugger:

a) The blue LED flashes after a power on, or press of the reset switch.

b) The red LED flashes after a rising edge on P3.3

#include "msp.h"
#include <stdint.h>

#define WAKEUP      BIT3
#define SPI_CS      BIT3
#define BLUE_LED    BIT2
#define GREEN_LED   BIT1
#define RED_LED     BIT0

static uint8_t RXData[100] = { 0 };
volatile uint8_t idx_RXData = 0;

void send_cmd_to_spi(uint8_t, uint8_t);

void boardInit(void);

int main(void) {
    WDT_A->CTL = WDT_A_CTL_PW |             // Stop WDT
            WDT_A_CTL_HOLD;

    __delay_cycles(1000000);

    // Initialize GPIO and clocks
    boardInit();

    // Check if the MCU is waking-up from LPM4.5
    if (PCM->CTL1 & PCM_CTL1_LOCKLPM5)
    {
        // Configuring P3 as output and P3.3 (switch) as input with pull-down resistor
        P3->DIR &= ~WAKEUP;
        P3->OUT &= ~WAKEUP;
        P3->REN |= WAKEUP;
        P3->SEL0 = 0;
        P3->SEL1 = 0;
        P3->IE |= WAKEUP;
        P3->IES &= ~WAKEUP; /*!< Port Interrupt Edge Select */

        // Clear LPM lock
        PCM->CTL1 = PCM_CTL1_KEY_VAL;
    }
    else
    {
        // Else it is a cold-start

        // Configuring P3 as output and P3.3 (switch) as input with pull-down resistor
        // Rest of pins are configured as output low
        P3->DIR = ~WAKEUP;
        P3->OUT &= ~WAKEUP;
        P3->REN |= WAKEUP;                     // Enable pull-down resistor (P3.3 output low)
        P3->SEL0 = 0;
        P3->SEL1 = 0;
        P3->IFG = 0;                        // Clear all P3 interrupt flags
        P3->IE |= WAKEUP;
        P3->IES &= ~WAKEUP; /*!< Port Interrupt Edge Select */

        // some BOOT led (blue)
        P2->OUT |= BLUE_LED;
        __delay_cycles(1000000);
        P2->OUT &= ~BLUE_LED;
    }

    // Turn off PSS high-side supervisors
    PSS->KEY = PSS_KEY_KEY_VAL;
    PSS->CTL0 |= PSS_CTL0_SVSMHOFF;
    PSS->KEY = 0;

    // Enable all SRAM bank retentions prior to going to LPM3 (Deep-sleep)
    SYSCTL->SRAM_BANKRET |= (SYSCTL_SRAM_BANKRET_BNK1_RET
            | SYSCTL_SRAM_BANKRET_BNK2_RET | SYSCTL_SRAM_BANKRET_BNK3_RET
            | SYSCTL_SRAM_BANKRET_BNK4_RET | SYSCTL_SRAM_BANKRET_BNK5_RET
            | SYSCTL_SRAM_BANKRET_BNK6_RET | SYSCTL_SRAM_BANKRET_BNK7_RET);

    // Enable global interrupt
    __enable_irq();

    // Enable Port 3 interrupt on the NVIC
    NVIC->ISER[1] = 1 << ((PORT3_IRQn) & 31);

    // Enter or Re-enter LPM4.5
    // Set the Power Mode 4.5
    PCM->CTL0 = PCM_CTL0_KEY_VAL | PCM_CTL0_LPMR__LPM45;

    // Do not wake up on exit from ISR
    SCB->SCR |= SCB_SCR_SLEEPONEXIT_Msk;

    // Setting the sleep deep bit
    SCB->SCR |= (SCB_SCR_SLEEPDEEP_Msk);

    // ---------------------------- start of spi section ----------------------------------

    // Set P1.5 CS low (but is active high)
    P1->DIR |= SPI_CS;
    P1->OUT &= ~SPI_CS;
    __delay_cycles(1000000);

    // Set P1.5, P1.6, and P1.7 as SPI pins functionality
    P1->SEL0 |= BIT5 | BIT6 | BIT7;

    EUSCI_B0->CTLW0 |= EUSCI_B_CTLW0_SWRST; // Put eUSCI state machine in reset
    EUSCI_B0->CTLW0 = EUSCI_B_CTLW0_SWRST | // Remain eUSCI state machine in reset
            EUSCI_B_CTLW0_MST |             // Set as SPI master
            EUSCI_B_CTLW0_MSB;              // MSB first

    // ACLK, /2, fBitClock = fBRCLK/(UCBRx+1), init USCI state machine
    EUSCI_B0->CTLW0 |= EUSCI_B_CTLW0_SSEL__ACLK;
    EUSCI_B0->BRW = 0x01;
    EUSCI_B0->CTLW0 &= ~EUSCI_B_CTLW0_SWRST;

    //send_cmd_to_spi(0x0a, 0x0b);

    // ---------------------------- end of spi section ----------------------------------



    __sleep();
    __no_operation();
    // For debugger

    // Blink LED slowly if LPM4.5 not entered properly
    while (1) {
        P1->OUT ^= BIT0;                    // XOR P1.0
        __delay_cycles(1000000);
    }
}

// Port 1 interrupt service routine
void PORT3_IRQHandler(void) {
    P1->OUT |= BIT0;                        // Set P3.3
    __delay_cycles(500000);
    P1->OUT &= ~BIT0;                       // Clear P3.3

    P3->IFG &= ~WAKEUP;                       // Clear P3.3 IFG
}

void boardInit(void) {
    // GPIO Port Configuration for lowest power configuration
    P1->OUT = 0x00;
    P1->DIR = 0xFF;
    P2->OUT = 0x00;
    P2->DIR = 0xFF;
    P3->OUT = 0x00;
    P3->DIR = 0xFF;
    P4->OUT = 0x00;
    P4->DIR = 0xFF;
    P5->OUT = 0x00;
    P5->DIR = 0xFF;
    P6->OUT = 0x00;
    P6->DIR = 0xFF;
    P7->OUT = 0x00;
    P7->DIR = 0xFF;
    P8->OUT = 0x00;
    P8->DIR = 0xFF;
    P9->OUT = 0x00;
    P9->DIR = 0xFF;
    P10->OUT = 0x00;
    P10->DIR = 0xFF;
    PJ->OUT = 0x00;
    PJ->DIR = 0xFF;
}

[I didn't check the power consumption when the MSP432 is sleeping in LPM4.5]