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EVM430-FR6043: Wake up from LPM4/x.5 using Timer A sourced by external clock

Ignacio Mendizabal
Prodigy 30 points

Part Number: EVM430-FR6043
Other Parts Discussed in Thread: MSP430FR6043,

Helo everyone,

I'm working on a project using the EVM430-FR6043 evaluation board as a template, we have timer A configured to interrupt every second to wake up the MSP430FR6043 from LPM3. Currently, timer A uses ACLK as source, which corresponds to an external 32.768 KHz oscillator on the EVM430-FR6043. I'd like to know if I can use the timer to wake up from other modes such as LPM4 or LPM4.5, from what I've seen on the datasheet, ACLK is disabled from LPM4 forward, except when using an external source (which is the case on this evaluation board), according to this, we should be able to still use Timer A to wake up the CPU. We tested this using the __low_power_mode_4() intrinsic, but according to the datasheet, the device will enter LPM3 if ACLK is requested, and as far as I know there is no way I can debug to know in which mode the device is currently in. 
I'd like to know if it's possible to wake up the device from LPM4 using a Timer A interrupt sourced by external ACLK, or if there is any way I can check the current LPM of the device. 
Thank you for your help.

  • 0
    TI__Mastermind 40195 points

    For the LPM mode, you can check it by current consumption or the register configuration. 

    What about use RTC, the current consumption will be lower.

  • 0 in reply to Eason Zhou
    Prodigy 30 points

    Thank you for your reply,

    Is it possible to check the SR while on LPM? Otherwise I'll think I'll have to measure the current consumption.
    I'm thinking of switching to the RTC, from what I've seen it's possible to wake up the MCU even from LPMx.5, however, on my current implementation I'm using a Timer A module, switching to the RTC may take me some time, and I'm looking for a quick fix for a proof of concept. That's why I was looking for a way to test LPM4 with Timer A. If it isn't possible, I guess I'll have to change my code as soon as possible.

    Ignacio

  • 0 in reply to Ignacio Mendizabal
    TI__Mastermind 40195 points

    You can see that only the RTC support to work under LPM3.5

    The reason lies on the crystal oscillator clock source is from crystal directly.

     As you said "the device will enter LPM3 if ACLK is requested, and as far as I know there is no way I can debug to know in which mode the device is currently in". You need to test current. Even the SR register shows you are at LPM4, if you require the clock, it will turns back to LPM3.

    Eason

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