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AM625: Wakeup crystal clock signal not coming

Premalatha Royappan
Intellectual 910 points
Part Number: AM625
Other Parts Discussed in Thread: SYSCONFIG

Hi 

We are using crystal input of 32.768KHz to the wake-up osc pins of AM625x. However, when we are trying to measure the clock frequency, we are not seeing any waveform.

We have enabled those pins in the sysconfig which are related to wakeup clock. Please let us know why we are not able to see any clk signal when we measure.

Schematics:

sysconfig:

  • 0
    TI__Genius 15333 points

    Hi Premalatha,

    Thank you for your query.

    I have taken your inputs and working on it. Please allow some time to revert back.

    Regards,

    Tushar

  • 0 in reply to Tushar Thakur
    TI__Mastermind 24790 points

    Hi Premalatha,

    Can you please confirm how you are checking the crystal oscillator waveform?

    Typically, the output of a crystal oscillator should be a sine wave with low amplitude, and low capacitance probes should be needed when you want to measure it.

    My suggestion is that instead of checking at the input side, you can check at the output side, like this crystal input is going to the different modules as timers, UART,I2C and other peripherals. Simply toggle a pin in Tmer IRQ and see exactly whether the timer is Running at your initialized frequency or not.

    This is one of the approaches, and I need to check if any other pins are there to monitor the CPU clocks.

    Regards,

    S.Anil.

  • 0 in reply to Swargam Anil
    Intellectual 910 points

    Hi Anil,

    We verified this wake up clock of 32.768khz in the evaluation board and observed the below ,

    However, in our design we are not able to see any clock. There isn't any issue with the crystal as the same part number crystal is used in another circuit in our design where it is working.

  • 0 in reply to Premalatha Royappan
    TI__Mastermind 24790 points

    Hello Premalatha,

    I am routing your question to HW expert to comment on the above issue.

    Regards,

    S.Anil.

  • 0 in reply to Swargam Anil
    TI__Guru 56685 points

    I would like to confirm the waveform you show in the oscilloscope capture represents the oscillation of the 32.768kHz crystal circuit. If so, it appears software has enabled the oscillator and it is working as expected.

    The next thing to check is the path through the device. I recommend using the clock tree tool to understand the various clock path options and make sure you have selected the appropriate path.

    Regards,
    Paul