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Original question:

TPL5010: relation of DONE and RSTn

TPL5010: How can I align the TPL5010 timing to system timing

Charles McClelland
Prodigy 250 points
Part Number: TPL5010
Other Parts Discussed in Thread: TPL5110

I have a number of posts on this forum but non seemed to address my issue directly please forgive me if I missed the answer.

I have a device that naps between sensor interrupts and wakes every hope at the top of the hour to report.  The process of napping / waking and reporting is already implemented.  I have the TPL5010 with a 1 hour 5 minute interval to reset the device if it does not report as the watchdog is "pet" during the reporting process.

Configuration:

- Wake  - from the TPL5010 goes to a GPIO pin on the microcontroller with a RISING interrupt

- Done - from the microcontroller to the TPL5010

- Reset - from the TPL5010 to the device's reset pin

- Two 270k resistors in parallel set an interval of just over 1 hour 

This solution requires some alignment of the watchdog interval to the hourly wake cycle.  If both are aligned, the device wakes at the top of the hour, pets the watchdog and goes to sleep.  The watchdog gets petted during the interval and therefore never needs to send a reset to the device.  If, however, the TPL5010 is not aligned to this interval, it will send WAKE signals during the hour and will cause the device to come out of napping state unnecessarily.  

Can I set the timing of the TPL5010's interval to align to the hourly schedule?  I had assumed that when I pet the watchdog, it would reset the next interval but apparently this is not the case.

Thanks, 

Chip

  • 0
    TI__Mastermind 18070 points

    Hello Chip,

    I'm afraid that the time interval of TPL5010 and the time interval of your other device cannot be set separately otherwise they won't be aligned. For your other device, instead of making it wake every hour, can you make it wake after a "WAKE" signal from TPL5010 kicks in? This is how TPL5010 is supposed to work, and I'm afraid I can't think of a way to force the alignment of two separately set time intervals.

    Regards,
    Hao

  • 0 in reply to Hao Z
    Prodigy 250 points

    Hao, 

    Thanks for answering - that is a bit of a bummer. 

    I need to report at the top of the hour - if I let the TPL5010 WAKE and set the reporting interval, it would walk all over the hours.

    Two questions:

    1) Is there another TI part which resets the Wake interval when the DONE pin is toggled?

    2) Perhaps I could use a pin on the microcontroller to turn off the power to the TPL5010, this would reset the device and, I HOPE / ASSUME / AM SURE (please help me pick one) would restart the timing interval.  If I take this approach, how long do I need to interrupt the power to accomplish this?  would 50mSec be enough?

    Thanks, 

    Chip

  • 0 in reply to Charles McClelland
    TI__Mastermind 18070 points

    Hi Chip, 

    According to Figure 9, RSTn is asserted at startup. So unless you have some sort of mask for the microcontroller when DONE is asserted, I don't think this is doable.

    There's another nano timer TPL5110, but it doesn't seem to work for your case either.

    Regards,

    Hao

  • 0 in reply to Hao Z
    Prodigy 250 points

    Hao, 

    Thank you for taking the time to research this.  So, it is these two defects (at least from my use case's perspective) that make this option a bad one:

    1) The inability to reset the "Wake" cycle using the Done or any other pin

    2) The Watchdog asserting a reset at power on so I could not use a GPIO pin on the uC to reset the watchdog's Wake cycle

    It is unfortunate that, in TI's large portfolio, there is not a solution.  But, again, thank you for you for your time.  

    Looks like I will need to use a small low power uC to make my own - ATTINY 202 for example.

    Chip