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LMK04033 defualting output to 54 MHZ

Sa De
Prodigy 135 points

Hi,

After programming the LMK with microwire protocol using various different set of registers. The clkout is giving 54 MHz irrespective of the changes in the registers.

What might be the reason?

I am giving the clkin0 and oscin0 a single ended clock of certain value continuously.

  • 0
    TI__Genius 10320 points

    Hi Sa De,

     A quick test to ensure the communication link is to program the POWERDOWN bit (R13:b17). Measure the current drawn by the device to see if communication between the device is correctly working.

    Can you cause the device to enter/exit POWERDOWN?

    Gabe

  • 0 in reply to Gabe Ayala
    Prodigy 135 points

    Thanks for reply, Gabe. I did verify the registers being programmed on the oscilloscope. During the programming of R7 register - I observed the frequency on clkout2 go down. and then come back again. And finally during the programming of r15 - the clkout2 sets to 54 MHz

  • 0 in reply to Sa De
    TI__Genius 10320 points

    Hi Sa De,

    The reason I asked to program this bit in particular is that one can monitor the state of the device without directly monitoring the output frequency or state. This allows us to ensure that the protocol is correct on the device side, which may not be apparent in a scope shot.

    Gabe

  • 0 in reply to Gabe Ayala
    Prodigy 135 points

    Gabe,

    Thanks for the idea. I did program Powerdown - could not observe any difference in the clock output. Where should I measure the power consumption, to ensure the correct programming?

    Should the reset bit also be programmed?

  • 0 in reply to Sa De
    TI__Genius 10320 points

    Hi Sa De,

    Since you did not notice a change in the output state when POWERDOWN was toggled, its a good indicator that your communication link is not working. If you are not using an EVM, the current consumption can be measured where the board supply plane branches to all device Vdd planes.

    Gabe

  • 0 in reply to Gabe Ayala
    Prodigy 135 points

    Hi Gabe,

    I am observing clkout2 go down 2 times. Once after the register 7 and once after the register 13.

    Sometimes it is defaulting to 23 MHz and other times the supply current goes to 0 and does not come back.

  • 0 in reply to Sa De
    TI__Genius 10320 points

    Hi Sa De,

    I suspect your uWire transactions are not working correctly. Can you provide scope plots of an example data transaction? Also, can you ensure the rise/fall, hold/setup times are being met?

    Gabe

  • 0 in reply to Gabe Ayala
    Prodigy 135 points

    Hi Gabe,

    I think the uwire transactions are working correctly at present as the LMK is able to powerdown if I set the powerdown bit.

    But, the problem is during the configuration when I am not using powerdown and to generate a clock frequency out from clkout2. Can you suggest any methods?

    Thanks

  • 0 in reply to Sa De
    TI__Genius 10320 points

    Hi Sa De,

    I do not understand your request. Can you please clarify?

    Gabe

  • 0 in reply to Gabe Ayala
    Prodigy 135 points

    Hi Gabe,


    The problem is solved now.

    Thanks