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Implementing a shutdown on Tiva C Microcontroller

Anand Meharwade
Expert 1090 points
Other Parts Discussed in Thread: TM4C123GH6PM

Hi All,

I am using TM4C123GH6PM part in one of the project,

The requirement is to implement shutdown feature for the system. The shutdown could be in the following sequence (suggest me if there is any better sequence):

  1. Disable all peripherals ICs
  2. Disable the microcontroller system clock
  3. Enter into sleep mode

I would like to know hardware setup also as I am not sure what would be the behavior of the nWAKE pin when controller is active state. I am using a single reset like switch. Can I connect it to nWAKE pin to put the system in shutdown on press and wake the controller and boot it once again on next press?

Is there any interrupt handler for nWAKE pin during active state of the controller.

Please help me as this concept is new to me.

For any more info feel free to ask me.

Looking forward to hear from you soon.

Regards

Anand M

  • 0
    TI__Guru**** 244400 points
    Hello Anand,

    I believe you mean Hibernate mode when you mean shutdown. If that is the case then

    The nWAKE pin is not like a toggle switch. It has to be pulled up to VBAT supply, where VBAT is a always ON supply like a coin cell. When the device is Hibernate mode, then the nWAKE has to be made low for the device to wakeup and re-boot. The nWAKE has to be low for 3 32K clock cycles which is supplied by a 32K oscillator. The rest of the system can be shutdown (they are automatically shut down so need to explicitly disable the peripherals and system clock)

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 117855 points

    Poster's  use of (undefined) "Shutdown" (as you noted) does concern.

    You've handled the MCU portion of course - but might the impact upon the larger "system" - in which the MCU is one part - deserve note, too?

    Amit - might you advise on the handling of critical, external devices - under MCU control - during this, "shutdown and/or hibernate?"

    Assume motors, actuators, logic inputs to power supplies, alarm inputs and remote (often serial bus connected) devices are present & active/enabled.  Should the controlling MCU-GPIO cease to (properly) "wind-down" - or meet the remote device's needs/specification during such shutdown - misfortune may result.

    Unusual for an MCU to exist by itself.   The needs of all system-connected devices must be well considered - and properly managed under all conditions - must they not?  

    Poster's (still unclear) expected goal of, "power-saving" has consequences - perhaps the detailing of GPIO behavior (and any other peripheral of consequence) during hibernate/shutdown - registers as a very related - and equally important - area for detailing...

  • 0 in reply to cb1_mobile
    Intellectual 520 points
    Hi, I believe Poster wants to implement a strategic power off sequence unlike hibernation. Having said that similar to a general purpose computing platform giving a command to shut down (instead of pulling off the power cord) should disconnect peripherals from supply one by one and then disconnecting the MCU itself(may need some nice hardware circuitry).