• State Resolved
  • Locked Locked
  • Replies 11 replies
  • Answers 3 answers
  • Subscribers 99 subscribers
  • Views 510 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM3358: Am3358

Cindy Lim
Prodigy 90 points
Part Number: AM3358
Other Parts Discussed in Thread: TPS65217

I would like to enquire, example if I have a limit switch connected to AM3358. 

once the limit switch is tamper, AM3358 will detect and perform some functions during power on and off state. 

in addition, there is a pin C5 external wakeup function. May i know how it works? thanks

Best Regards,

Cindy

  • 0
    TI__Guru**** 171581 points

    HI Cindy,

    I am routing your query to our HW expert for comments.

  • 0 in reply to Bin Liu
    TI__Guru 63235 points

    The pin you are asking about can be used to wake the device from the RTC domain when it is the only portion of the part of the device that has power. It sounds like you want the software of a normally functioning system to detect this event and take a specific action. Any pin with a GPIO signal function can be configured to generate an interrupt. This will be your best approach.

    Regards,
    Paul

  • 0 in reply to peaves
    Prodigy 90 points

    Is it available when power off state?

    How to implement this? 

  • 0 in reply to Cindy Lim
    TI__Guru 63235 points

    Please provide more details of what you are trying to do.

  • 0 in reply to peaves
    Prodigy 90 points

    i would like to have a circuitry where when my MCU=AM3358 is in power off state. I can trigger a gpio to the PMIC to wakeup my MCU-3358 to perfom some function with the MCU at very low power state

    in addition, how do i use the RTC on the MCU-AM3358

  • 0 in reply to Cindy Lim
    TI__Guru 63235 points

    For the AM335x use case described above, the RTC is always powered and provides a Real-Time Clock function with a few additional capabilities. The RTC has a wake input and a PMIC power enable output, where it can be configured to detect an external wake event on its wake input and turn on the PMIC with its PMIC power enable output when the PMIC is off. The RTC also has the capability of scheduling a time to turn on the PMIC back on after it was previously turned off. Everything except the RTC domain in AM335x is powered off when the PMIC turns off, so the AM335x must reboot its operating system each time it is powered on. This mode of operation is not a deep sleep mode where you can quickly return to a previous state. The PMIC must remain on and you would need to use one of the various low power modes supported by AM335x if you need to return to a previous state.

    All of these details are provided in the AM33x TRM. So you need to read the TRM to understand how these hardware functions operate. You may find it helpful look at software examples to understand how all these low power modes are configured by your respective operating system. I'm not familiar with AM335x software, so will not be able to answer any software related questions. I can reassign your post to the respective software team if you have any specific software questions.

    Regards,
    Paul

  • 0 in reply to peaves
    Prodigy 90 points

    how do i maintain the rtc when the MCU is powered off?

  • 0 in reply to peaves
    Prodigy 90 points

    how do I maintain the RTC when the MCU is powered off? as when there is no 5V, my PMIC will not work?

  • 0 in reply to Cindy Lim
    TI__Guru 63235 points

    The RTC circuits in AM335x have their own power supply pins. So you would need to power these pins with an always on power source.

  • 0 in reply to peaves
    Prodigy 90 points

    Currently my design consist of both TPS65217 & AM3358. Any idea how I can implement both the sleep state and RTC.

    what the current consumption?

    what is the drift factor for the RTC module inside AM3358?

  • 0 in reply to Cindy Lim
    TI__Guru 63235 points

    The RTC logic in AM335x does not play any role in the various low-power sleep states support by AM335x while power remains on. These low-power sleep states are defined by software, where clocks are stopped for some logic functions and clock frequency reduced for other logic functions. You need to research the various modes supported by your operating system.

    The Power Estimator Tool is the best way to understand current consumption based on your specific use case.

    The RTC drift will be a function of the crystal circuit you connect to the RTC oscillator. In a typical application the RTC is constantly updated by the processor operating system while it has power, which gets its time from a accurate on-line time source. The RTC only needs to keep time while the processor is turned off. The off-time is typically short relative the time it takes for the drift to be a concern. The RTC will be updated by the operating system again after it turns on the PMIC, the processor boots the operating system, and it gets access to an accurate on-line time source.

    Based on your questions, you have not read the TRM or researched what is supported by software. I will not be able to talk you through all of these details. You need to research your options.

    Regards,
    Paul