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How can MSP430F6633 in LPM3.5 and RTC_B mode implements A/D transfer every interval like 2-Second itself alone ?

Other Parts Discussed in Thread: MSP430F6633

I'm going to let the RTC_B enabled MSP430F6633, which in LPM3.5 mode,  implements A/D transfer every interval like 2-Second itself alone ,sometimes it may be wake up by calendar alert from LPM3.5 mode  to implements A/D transfer,not any button be pushed ,can my desire achieve ?How can I do about this ? can you tell me detailed ?

  • In LPM3.5, there's almost everything down except the RTC. So you can wakeup the MSP by the calendar, but all timers are stopped and hardware off. Else it wouldn't be LPM3.5.
    You can trigger the ADC with a timer to do a conversion every 2 seconds if you have the ADC acive (it won't start and perform necessary settlign delays if you just trigger it - it has to be ready all the time) and have a timer running. Or you have a timer running, and the ADC inactive, and every 2 seconds you wakeup the CPU, let it setup the ADC and wait for the settling times, then do the conversion).

    The timer might be the RTC (if you program and update the calendar interrupt for 2s intervals) if you want to wakeup the CPU. The RTS cannot, however, trigger a conversion.

    Anyway, keeping the CPU active for the time to fire up the ADC and do the sample might take more power than leaving the ADC active and use a different LPM for the sleep time.

    And what do you do with the sampled data? Just leave it there for overwrite? Not likely. So you already need the CPU.

  • I am designing  a battery powered instrument ,It must consume lowest power and have 2 function:1,calendar;2,ADC conversion.

    About ADC,one work mode is:every interval,to do an ADC,if the data bigger than the expected data ,exit from lowest power mode into active mode and always implement in active mode;else,discard the data and return into the lowest power mode.

    its another work mode is:when a calendar alert happened,exit from lowest power mode into active mode and always implement in active mode; else,discard the data and return into the lowest power mode.

    please give me some advice ,what LPMx mode of F6633 can I use ? how can I do about this ? if the voltage of battery connected in VBAT lowered,can I charge it through the pin ? 

    Thank you for your help !

  • I have not worked with the F6633 before and in my projects, power-savinf was never an issue. So I cannot tell you anything that isn't already in teh datasheet or users guide.

    If you have specific problems with implementation details (teh 'how'), I'll be glad to be of further help, but for the 'what', the more general hints I have given are the limit.

    Perhaps someone who has alread done a low power project with this device can tell you his experiences. But then, if there were a solution already, you wouldn't have a project :)

  • Thanks for your help !

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