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MSP430FR6972: how to use MSP430 internal watchdog

aiwen chen
Intellectual 625 points
Part Number: MSP430FR6972
Other Parts Discussed in Thread: TPL5010,

Our customer's instrumentation mainly uses the hardware design scheme of TPL5010+MSP430. Now I want to remove the external watchdog IC and use the MSP430 internal clock as a watchdog，As shown in the figure below, we want to remove this part of the circuit and directly control it by the MSP430。

External 8s clock timing to prevent MCU downtime and affect water metering。They want to remove the external watchdog IC TPL 5010, using MSP430 internal watchdog, is this method OK? Are there any reference designs and applications?

  • 0
    TI__Expert 5040 points

    Hello,

    For the MSP430FR6972, the internal watchdog timer (WDT) is available through SMCLK and ACLK. 

    For reference code, please see the examples linked here. There are a few different examples for the WDT at the very bottom of the list.

    In addition, you can look at the MSP430 WDT academy linked here for an introduction to using an internal watchdog on a MSP430 device.

    Thank you,

    Susan 

  • 0 in reply to Susan Moore
    Intellectual 625 points

    Hi  dear;

     1. My customers are worried about the stability of the internal watchdog, they mainly do water meter measurement, need to read the data at any time, if the oscillation source is unstable, will it cause the program to be abnormal and not execute the instruction? And will it lead to errors in meter metering?

     2. Can an internal watchdog be used in the application of water meters? Please help to evaluate, will there be an unstable internal oscillation source? What is the probability? What factors are involved?

  • 0 in reply to aiwen chen
    TI__Expert 5040 points

    Hello,

    An unstable oscillation source can cause issues with any timer, not just the internal watchdog. If using an external oscillation source (which would grant you better accuracy), I would make sure it is stable.

    If you are just planning on using an internal oscillation source, the internal watchdog itself is stable and reliable as long as it is configured correctly for your application. For 8 second sampling, a 32KHz oscillator or the VLO should be able to easily attain that.

    Factors affecting the WDT are mostly the power mode chosen and the clock source.

    Thank you,

    Susan

  • 0 in reply to Susan Moore
    Intellectual 625 points

    Hi ;

    1、If something goes wrong with the MCU jammed software, the internal watchdog won't work, right?

    2、A long time ago, my client used the msp430 internal watchdog, but at that time the internal oscillation source problem caused the function to be abnormal. Is this happening now? Is the internal process structure of the msp430 now the same as it was 10 years ago?

  • 0 in reply to aiwen chen
    Intellectual 625 points

    Is the internal process optimized compared to the previous MSP430?

  • 0 in reply to aiwen chen
    Guru 25275 points

    The purpose of the internal watchdog timer (or any watchdog) is to reset the processor if something goes wrong.Giving it a chance to recover to something resembling normal operation.

    It appears that you are using it for timing. Why not just use the normal timers (and low power modes)? Leaving the watchdog to do what it was designed to do.

  • 0 in reply to David Schultz
    Intellectual 625 points

    1. Now we take the TPL5010 external 8s clock to feed the dog regularly to prevent the MCU from going down and affecting the metering of water. If I use the internal watchdog to achieve 8-second timed feeding of the dog, is this feasible?

    2. If there is a problem with the internal oscillation source, it may affect the performance of my internal watchdog, how to use the internal watchdog to feed the dog regularly when the oscillation source has a problem, do I need to add another timer? Does this mean that even with an internal watchdog, do we still need to use a normal timer to keep the time?

  • 0 in reply to aiwen chen
    TI__Expert 5040 points

    Hello,

    Can you clarify what you are trying to do with the internal watchdog? As in, can you explain what you mean by achieving an 8-second timed feeding of the dog? 

    If you are using it just as a timer, I would just use a timer. As David stated, the watchdog is there to reset the MCU if there is a problem with the software. While it can be configured as a timer if desired, there are plenty of other timers that can be used as well so that you still have the watchdog there to reset the system if there is a software issue.

    Thank you,

    Susan

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