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IWR1642: What's the frequency of OSC_CLKOUT (A14)?

Chris Meng
Mastermind 37646 points
Part Number: IWR1642

Hi,

In datasheet, it only explained that OSC_CLKOUT is Reference clock output from clocking sub system after cleanup PLL. But what's the frequency? Will it change based on chip configuration or it is a fixed frequency?

Thanks,

  • 0
    TI__Guru 58035 points
    Hello Chris,
    In case of IWR1642 device OSC_CLKOUT is a pin used for debug purpose only. The user can enable bringing out the APLL clock (1.8Ghz) or a divided version of the synth (2.5/5Ghz) on this pin.

    regards,
    Vivek
  • 0 in reply to Vivek Dham
    TI__Mastermind 37646 points
    Vivek,

    How to enable the OSC_CLKOUT and configure it? In TRM, I only found info related to MCU_CLKOUT. Does the MCU_CLKOUT refer to OSC_CLKOUT? If not, would you pls kindly advise how enable and configure the OSC_CLKOUT?

    Thanks,
  • 0 in reply to Chris Meng
    TI__Guru 58035 points
    Hello Chris,
    Presently we do not have an API to enable debug signals on the OSC_CLKOUT. We will be adding this in the future releases.
    MCU CLKOUT and OSC CLKOUT are seperate.

    Regards,
    Vivek
  • 0 in reply to Vivek Dham
    TI__Mastermind 37500 points

    Hello Chris,

    We have asked one of the designers for the functions, bit definitions that match the TRM Figure 3-1 for the clock subsystem.   From Vivek's description, the preliminary answer is the OSC_CLKOUT frequency  matches the APLL output frequency, and the divider programmed.  

    In  IWr14 device, the APLL frequency would be based on the highest speed peripheral which is HSI(LVDS/CSI-2).    

    Given an external crystal at 40Mhz, and an 1800Mhz output, the feedback divider would be 45.  In this case the OSC_CLKOUT would be 1800Mhz.

    I think it would be a better idea to divide this signal back down to < 150Mhz for single ended CMOS use.  

    In the datasheet IWr16, under the pinmux table, Table 4-1, K13, you can select the PMIC_CLKOUT, using addrexx 0xFFFFEA64 to select the PMIC_CLKOUT

    I think the proper divider is 1800/2 = 900, for a 2Mhz output.

    We will send more of an update, when the designer has provided more information.

    Regards,

    Joe Quintal

  • 0 in reply to Radio-Joe
    TI__Mastermind 37500 points
    Hello Chris,
    The OSC_CLKOUT is only enabled on devices that are configured with CASCADE enabled. The OSC_CLKOUT should match the input crystal frequency. On a standard radar sensor, you would need to use MCU_CLKOUT, or PMIC_CLKOUT/
    REgards,
    Joe QUintal