MSP430FR2422: disabling the SVS (reducing current while in LPM3.5)

Hi Stefan,

I will respond within 24hrs.

Hi Stefan,

Yes, you should be able to do this.  So you are saying the reset occurs just after disabling the SVS?  Are you using the correct PW (0xA500)?

 Can you reduce the size of your code to smallest possible, but still demonstrates this issue, and attach to your response.

Hi Dennis,

yes I checked the password twice. As you can see I used the official #define in the msp430fr2422.h file. Here #define PMMPW_H    (0x00a5), where only the higher 16bit will be written into the PMMCTL0 register... 

Now, I send you my complete source code hoping that you might find a bug. :-)

Thank you so much (for the review)!!!

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#include <msp430.h>

void initGpio(void);

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD | WDTSSEL__VLOCLK;               // Stop WDT, watch clock source = VLO

    initGpio();                             // Configure GPIO

    // First determine whether we are coming out of an LPMx.5 or a regular RESET.
    if (SYSRSTIV == SYSRSTIV_LPM5WU)        // When woken up from LPM3.5, reinit
    {
        // If MCU wakes up from LPM3.5, re-init and then return to LPM3.5 again.

        // Restore P1OUT value from backup RAM memory, keep P1OUT after LPMx.5 reset
        P1OUT = *(unsigned int *)BKMEM_BASE;

        __enable_interrupt();               // The RTC interrupt should trigger now...
    }
    else
    {
        // Device powered up from a cold start.
        // It configures the device and puts the device into LPM3.5

        // disabling the SVS (Supply Voltage Supervisor) by setting SVSHE = 0

        // Open PMM registers for write access
        PMMCTL0_H = PMMPW_H;

        // clear SVSHE bit
        PMMCTL0 &= ~SVSHE;
        // Lock PMM registers for write access
        PMMCTL0_H = 0x00;


        // Configure backup memory
        *(unsigned int *)BKMEM_BASE = 0;

        // Configure RTC (clock source = VLO)
        // Interrupt and reset happen every 1024/10000 * 150 = 15,6 sec.
        RTCMOD = 150-1;
        RTCCTL = RTCSS__VLOCLK | RTCSR |RTCPS__1024;
        RTCCTL |= RTCIE;

        // Store P1OUT value in backup memory register before enter LPM3.5
        *(unsigned int *)BKMEM_BASE = P1OUT;
    }

    // do something for 5 sek (~216uA @1MHz)
    __delay_cycles(5000000);


    // Enter LPM3.5 mode with interrupts enabled. Note that this operation does
    // not return. The LPM3.5 will exit through a RESET event, resulting in a
    // re-start of the code.
    PMMCTL0_H = PMMPW_H;                    // Open PMM Registers for write
    PMMCTL0_L |= PMMREGOFF;                 // and set PMMREGOFF
    __bis_SR_register(LPM3_bits | GIE);

    __no_operation();  // for debug only (never reached)

    return 0;
}

void initGpio(void)
{
    P1DIR = 0xFF; P2DIR = 0xFF; P3DIR = 0xFF;
    P4DIR = 0xFF; P5DIR = 0xFF; P6DIR = 0xFF;
    P1REN = 0xFF; P2REN = 0xFF; P3REN = 0xFF;
    P4REN = 0xFF; P5REN = 0xFF; P6REN = 0xFF;
    P1OUT = 0x00; P2OUT = 0x00; P3OUT = 0x00;
    P4OUT = 0x00; P5OUT = 0x00; P6OUT = 0x00;

    // Disable the GPIO power-on default high-impedance mode
    // to activate previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;
}

#pragma vector = RTC_VECTOR
__interrupt void RTC_ISR(void)
{

    switch(__even_in_range(RTCIV, RTCIV_RTCIF))
    {
        case RTCIV_NONE : break;            // No interrupt pending
        case RTCIV_RTCIF:                   // RTC Overflow
            // Toggle LED on P1.0
            P1OUT ^= BIT0;

            // Store P1OUT value in backup memory register
            *(unsigned int *)BKMEM_BASE = P1OUT;
            break;
        default:          break;
    }
}