CCS/MSP432P401R: RTC runs fast

Robert,

<<< I found a description in the 2015 432 user's guide that makes the oscillator faut feature seem complicated to set up and use.
<<< It appears to generate an NMI interrupt when a fault count is exceeded. Is this correct?

2015 432 users's guide? Do you have red, black? Which chip revision? We should base on an a TRM (tech. ref. man.) version valid for your chip.
According to the latest TRM, oscillator fault does not seem complicated.

TRM:

LFXT_OscFault:
This signal is set after the LFXT oscillator has stopped operation and is cleared after operation resumes. The fault condition causes LFXTIFG to be set and remain set. If the user clears LFXTIFG and the fault condition still exists, LFXTIFG is set again.

NOTE: Fault logic As long as a fault condition still exists, the individual fault flags remains set. The clock logic switches back to the original user settings before the fault condition when the fault condition is resolved and the corresponding fault flag is cleared.

6.2.11 Start-up Counters The LFXT includes a counter that makes sure that a programmable number of clock cycles have passed before the LFXT_OscFault signal is cleared. The counter can be programmed from 4096 to 32768 counts using the FCNTLF bits. The default is the maximum count. Any crystal fault restarts the counter. It is also possible to restart the counter directly through software by setting the RCNTLF bit.

No doubts you know how to deal with it.
Please give us a feedback about your findings.

Many thanks for an opportunity to learn how to deal with the clock faults!

Calibration cannot exceed of ±240ppm.
In your issue like about -90,000 is needed.

THere is also a timeout API.  

CS_startLFXTWithTimeout(uint32_t xtDrive, uint32_t timeout)

Also, confirming Tmoasz comment, in this API the maximum drive strength is applied and then once the crystal has started the drive strength is changed to the parameter passed in the API.

I have found this to be a good reference for the LFXT, 

Regards,

Chris

I used the below program on my MSP432P401R redboard. Note that until I put the timeout, CS_startLFXT() did not return.

I ran it for 565 seconds according to the stopwatch in my watch and the elapsed time according to the program was 564 seconds - within my margin of error.

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 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * --/COPYRIGHT--*/
/*******************************************************************************
 * MSP432 SysTick - Blink LED Program
 *
 * Description: This program will use the SysTick module to blink an LED with
 * a one second period. Once setup, the application will go into LPM3
 * mode and only wake up to toggle the GPIO pin.
 *
 * This program runs infinitely until manually halted by the user.
 *
 *                MSP432P401
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST         P1.0  |---> P1.0 LED
 *            |                  |
 *            |                  |
 *            |                  |
 *            |                  |
 *            |                  |
 *
 *******************************************************************************/
/* DriverLib Includes */
#include <ti/devices/msp432p4xx/driverlib/driverlib.h>

/* Standard Includes */
#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>

 static volatile RTC_C_Calendar newTime;

// Time is Saturday, November 12th 1955 10:03:00 PM */
 const RTC_C_Calendar currentTime =
 {
         0x00,
         0x03,
         0x22,
         0x06,
         0x12,
         0x11,
         0x1955
 };

volatile unsigned int Tick;
volatile int i;

//![Simple SysTick Example]
int main(void)
{
    volatile unsigned int stash;
    uint_fast8_t rtcs;
    uint_fast8_t rtcm;
    int sec, mins;

    /* Halting the Watchdog */
    MAP_WDT_A_holdTimer();

    /* Configuring GPIO as an output */
    MAP_GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN0);

    // Configure the clock
    /* Just in case the user wants to use the getACLK, getMCLK, etc. functions,
     * let's set the clock frequency in the code.
     */
    CS_setExternalClockSourceFrequency(32000,48000000);

    /* Starting HFXT in non-bypass mode without a timeout. Before we start
     * we have to change VCORE to 1 to support the 48MHz frequency */

    MAP_PCM_setCoreVoltageLevel(PCM_VCORE1);
    MAP_FlashCtl_setWaitState(FLASH_BANK0, 1);
    MAP_FlashCtl_setWaitState(FLASH_BANK1, 1);
    CS_startHFXT(false);
    CS_startLFXTWithTimeout(CS_LFXT_DRIVE3, 256);

    /* Initializing MCLK to HFXT (effectively 48MHz) */
    MAP_CS_initClockSignal(CS_MCLK, CS_HFXTCLK_SELECT, CS_CLOCK_DIVIDER_1);
    MAP_CS_initClockSignal(CS_BCLK, CS_LFXTCLK_SELECT, CS_CLOCK_DIVIDER_1);
    //![Simple CS Config]

    MAP_RTC_C_initCalendar(&currentTime, RTC_C_FORMAT_BCD);


    MAP_SysTick_enableModule();
    MAP_SysTick_setPeriod(48000); // every 1 ms?
    MAP_SysTick_enableInterrupt();

    /* Enabling MASTER interrupts */
    MAP_Interrupt_enableMaster();

    printf("Hello, World!\n");
    fflush(stdout);

    MAP_RTC_C_startClock();

    while (1)
    {
        for (i=0; i<3000000; i++) /* delay */;

        MAP_SysTick_disableInterrupt();
        stash = Tick;
        MAP_SysTick_enableInterrupt();


            newTime = RTC_C_getCalendarTime();
            rtcs = newTime.seconds;
            rtcm = newTime.minutes;
            sec = RTC_C_convertBCDToBinary(rtcs);
            mins = RTC_C_convertBCDToBinary(rtcm);
            printf("RTC_min = %d, RTC secs = %d\n",mins, sec);
            fflush(stdout);
    }
}

void SysTick_Handler(void)
{
    Tick++;
}
//![Simple SysTick Example]

Keith,

<<< Note that until I put the timeout, CS_startLFXT() did not return.
I need to elaborate that.
Worth to reproduce!

As I remember, I have 2 reds and 2 blacks.
I will focus on reds. Regarding blacks, if needed, based on reds results, it would take some time for a proper setup.

Weekend is coming, time for sailing and based on a weather conditions I might not respond till Mon.

"Note that until I put the timeout, CS_startLFXT() did not return."

If you used the timeout, how did you know the call completed successfully?

IDid you check the status of the return value?