MSP432P4111: RTC Battery Backup

Hi Chris,

Thanks for confirming. I believe both the main battery and backup batteries will be non-rechargeable.

Regards,
Akash

Hi Chris,

Do we have any sample code that shows the detection of the main battery removal event and puts the MSP432 into LPM3.5 with the RTC running?

I see in TI-REX we have a few different examples: powerdeepsleep, powersleep, and powershutdown. What LPM is the MSP432 going into for each of those examples?

Regards,
Akash

Akash,

   Unfortunately, we do not.  This would be a combination of two peripherals (ADC+RTC) and the examples generally only highlight one peripheral at a time.  In concept you could take the temperature sensor example and update for the Vcc/2 monitor and then combine with the RTC.

    ADC14_initModule(ADC_CLOCKSOURCE_MCLK, ADC_PREDIVIDER_1, ADC_DIVIDER_1,
            ADC_TEMPSENSEMAP);

    /* Configuring ADC Memory (ADC_MEM0 A22 (Temperature Sensor) in repeat
     * mode).
     */
    ADC14_configureSingleSampleMode(ADC_MEM0, true);
    ADC14_configureConversionMemory(ADC_MEM0, ADC_VREFPOS_INTBUF_VREFNEG_VSS,
            ADC_INPUT_A22, false);

Where TEMPSENSEMAP would become BATTMAP and ADC_INPUT_22 would become 23.

Additionally, you can also use the built in comparator function to automatically trip (interrupt) when the voltage falls below a certain value.

Chris

Akash,

  In response to Chris's post-

 What you are looking for is a power-muxing switch. TI offers devices that can be used to build one and has an App Note on Power Muxing here that describes how to do it.  Section 4 shows a seamless-switchover MUX that would automatically handle switching to the backup supply if the primary fails. The PG signal (which indicates use of the secondary) can be used to tell the system to go into LPM3/x modes.  (I would also recommend a periodic wakeup from LPM3 using a timer, etc, to ensure you don't get stuck in backup mode due to a glitch on the PG signal).

-Bob L.