MSP430FR5969: Counting external pulses with minimum power consumption

Koichiro Tashiro

Hi,

My customer wants to count incoming pulse edges with MSP430FR5969.

I think it is possible to connect the signal to Timer-A CLK.
For example, TA0CLK (P1.2) can be used.

To minimize power consumption, the chip is in LPM and periodically waken up by an external interrupt or RTC.
In this case;
- Timer is clocked by an external clock from P1.2
- RTC is clocked by 32k VFXT Oscillator
So I guess LPM4 can be used, correct?

Thanks and regards,
Koichiro Tashiro

over 6 years ago

0 Lixin Chen1 over 6 years ago

TI__Expert 7015 points

Hi, Koichiro,

Yes. LPM4 can be used in this case: .

- Timer is clocked by an external clock from P1.2
- RTC is clocked by 32k LFXT Oscillator

Regards,

Lixin

0 Koichiro Tashiro over 6 years ago in reply to Lixin Chen1

TI__Mastermind 22945 points

Hi Lixin,

Thanks for your reply.
Could you confirm one point?

According to user’s guide, Figure 1-5 and Table 1-2, OSCOFF=1 and all clocks are disabled in LPM4.
Still LFXT OSC can be used for RTC in LPM4?

Thanks and regards,
Koichiro Tashiro

0 Lixin Chen1 over 6 years ago in reply to Koichiro Tashiro

TI__Expert 7015 points

Hi, Tashiro,

The answer is YES - LFXT OSC can be used for RTC in LPM4.

In fact, the XT1CLK and VLOCLK can be active during LPM4 if requested by low-frequency peripherals. You can find the NOTE after table 6-1 in the MSP430FR2355 datasheet.

We have found there is some description mismatch in the MSP430FR5xx/6xx document for the LPM4 power mode. And the system team is working on the document update and will be released in next quarter. Thanks for your feedback.

Best Regards,

Lixin

0 Lixin Chen1 over 6 years ago in reply to Lixin Chen1

TI__Expert 7015 points

Hi, Tashiro,

Do you have any other questions?

If my comment is helpful to resolve your questions, please click on the This resolved my issue button to close this thread.

Best regards,

Lixin

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MSP430FR5969: Counting external pulses with minimum power consumption