MSP430F6726A: Regarding XT1 fault detection

user5994067

Intellectual 820 points

Part Number: MSP430F6726A

Hi,

What are the conditions for XT1LFOFFG to be 1 from 0 in LF mode?

Also, the default after resetting this register is 1, but is it necessary to reset it to 0 by software after resetting?

Best regards,

over 3 years ago

0 Aaron Barrera over 3 years ago

TI__Mastermind 26046 points

Hello,

XT1LFOFFG will be a 1 if an XT1 fault condition exists. It will continue to be a 1 unless cleared by software. You should clear the flag in software after resetting to ensure that there isn't actually an XT1 oscillator fault.

0 user5994067 over 3 years ago in reply to Aaron Barrera

Intellectual 820 points

Hi,

thank you for your answer.

After changing to XT1LFOFFG = 0 by software,

is the condition that fault detection works and XT1LFOFFG = 1

is when the oscillation frequency of XT1 deviates from 32768Hz by 50ppm or more?

Best Regards,

0 Aaron Barrera over 3 years ago in reply to user5994067

TI__Mastermind 26046 points

Hello,

Sorry for the delay in response, I appreciate your patience.

I am checking internally with the apps and design team and get you a response on Monday.

0 Aaron Barrera over 3 years ago in reply to Aaron Barrera

TI__Mastermind 26046 points

Hello,

The best information I could find is footnote 7 of Table 5-2 in the datasheet:

"Frequencies below the MIN specification set the fault flag. Frequencies above the MAX specification do not set the fault flag. Frequencies in between might set the flag."

Therefore, if the frequency deviated by more than 50ppm at 32678 Hz, the fault flag is not set in LF mode since the MAX Oscillator fault frequency is 10kHz.

0 Aaron Barrera over 3 years ago in reply to Aaron Barrera

TI__Mastermind 26046 points

Hello,

Do you need more information about this? I saw you rejected the answer.

0 user5994067 over 3 years ago in reply to Aaron Barrera

Intellectual 820 points

Hi,

Thank your answer.

I understand that.

Best regards,

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MSP430F6726A: Regarding XT1 fault detection