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TM4C123x hibernation clock source

Engin Bilgin
Prodigy 80 points
Other Parts Discussed in Thread: TM4C123GH6PM

Hello Friends,

I am currently writing the firmware for a TM4C123GH6PM based project designed and prototyped by my predecessor. The board has sleep functionality activated by a button triggering the !WAKE pin of the MCU. The circuit however has no crystal or oscillator connected to the XOSC pins of the MCU, XOSC0 is grounded and XOSC1 is left not connected. From the schematics notes I understand that the design choice was made with the intention of using the internal low frequency oscillator (HIB LFIOSC).

Is it possible to use an internal low frequency oscillator to clock the hibernation module in the TM4C123x series MCU's? From what I can see, a hibernate low frequency oscillator is mentioned in two places in the datasheet, on pages 59 and 1375, but no detailed information is available as to how to configure and use it. I can see it is available to the hibernation modules in the TM4C129x series but I cannot find any information in TM4C123x series datasheets. There is one low frequency oscillator LFIOSC in TM4C123x but I understand it is available for Sleep and Deep-Sleep modes only.

Am I perhaps overlooking a detail? Your comments are most appreciated.

Regards,

Engin

  • 0
    TI__Mastermind 22580 points
    Hello Engin,

    From the datasheet of the TM4C123 device, it does not look like you can use an internal clock source for the Hibernation module. You will need an external crystal or external oscillator to provide clock to the hibernation module. The HIBCTL register is where the clocking control would be available and it is absent for TM4C123 devices.

    I am not sure what else can be done to use the Hibernation module with the current hardware setup.

    Thanks,
    Sai
  • 0 in reply to Sai Reddy
    Prodigy 80 points

    Thank you Sai, looks like I'll need a PCB revision to get hibernation working.
    Regards,
    Engin