MSP430F6769A: RTC C Trouble Writing to RTCTCMP after a write to RTC0CAL

Carl Hawes

Part Number: MSP430F6769A

After a write to RTCOCAL (Crystal Compensation) I need to apply/re-apply the temperature compensation via the RTCTCMP register, however according to the debugger (CCS10.1.0, MSP-FET430UIF) this write is failing....

After I write to RTCOCAL... the debugger says that RTCTCMP_L == RTCOCAL_L. (the value I have written to RTCOCAL has also been written to RTCTCMP!)
After a write attempt using the rtc_c.c library function RTC_C_setTemperatureCompensation() RTCOCAL_L resets to 0.. this maybe is concurrent with the user guide slau208q, where it states that writing to RTCOCAL resets RTCTCMP. However I was not expecting that behaviour, I was expecting that the write to RTCOCAL would immediately reset RTCTCMP, then I would be able to update it...
Subsequent write attempts, although seemingly successful (RTC_C_setTemperatureCompensation() returns STATUS_SUCCESS) do not according to the debugger update RTCTCMP_L, it remains 0

bool RTC_C_setTemperatureCompensation(uint16_t baseAddress,
                                      uint16_t offsetDirection,
                                      uint8_t offsetValue)
{
    while(!(HWREG8(baseAddress + OFS_RTCTCMP_H) & RTCTCRDY_H))
    {
        ;
    }

    HWREG16(baseAddress + OFS_RTCTCMP) = offsetValue + offsetDirection;

    if(HWREG8(baseAddress + OFS_RTCTCMP_H) & RTCTCOK_H)
    {
        return(STATUS_SUCCESS);
    }
    else
    {
        return(STATUS_FAIL);
    }
}

Does anyone have a clue to what is going on?

Best Regards
Carl

over 4 years ago

0 Christoph Schweers over 4 years ago

Intellectual 475 points

Hi Carl,

RTCOCAL is 'Key Protected'. First, RTCKEY must be written to unlock the RTC_C module.

Best regards

Christoph

0 Carl Hawes over 4 years ago in reply to Christoph Schweers

Prodigy 80 points

Thanks Christoph

But I am aware of that, I can successfully write to RTCOCAL, that is not my issue... once I write to RTCOCAL, It would appear that I cannot write to RTCTCMP, or at least it does not update via the debugger.

Kind Regards

Carl

void RTC_C_setCalibrationData(uint16_t baseAddress,
                              uint8_t offsetDirection,
                              uint8_t offsetValue)
{
    HWREG8(baseAddress + OFS_RTCCTL0_H) = RTCKEY_H;
    HWREG16(baseAddress + OFS_RTCOCAL) = offsetValue + offsetDirection;
    HWREG8(baseAddress + OFS_RTCCTL0_H) = 0x00;
}

0 JohnS over 4 years ago in reply to Carl Hawes

TI__Guru**** 161500 points

In the register view in CCS if you right click on RTCTCMP and select View memory at address it will open a memory view showing the memory that these registers are mapped to.

Do you see the expected values there?

Regards,

John

0 Carl Hawes over 4 years ago in reply to JohnS

Prodigy 80 points

Hi John/Christoph.

Sorry for the delay in getting back to you, I got pulled off the RTC compensation task, and havent had the chance to get back to it till today.

The problem would seem to be related CCS 10.1 or perhaps a project file corruption. I have since updated to CCS 10.2.00009, and did a clean project creation and the problem has corrected itself.

Although the debugger does not extactly behave as outlined in the datasheet, I can now successfully modify the contents of RTCTCMP after I have modified RTCOCAL

Registers before Modification

RTCOCAL = 0x0000

RTCTCMP = 0xC000

Registers After write to RTCOCAL

RTCOCAL = 0x0010 (Memory contents match register contents)

RTCTCMP = 0x4010 (Note how RTCTCMP has not been 'reset' as it states in the datasheet)

Registers After write to RTCTCMP

RTCOCAL = 0x0010

RTCTCMP = 0xE007

Many Thanks for your support in this matter

Carl

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MSP430F6769A: RTC C Trouble Writing to RTCTCMP after a write to RTC0CAL