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TMS570 Halcogen Dual clock Comparator

enrico terraneo
Intellectual 695 points
Other Parts Discussed in Thread: HALCOGEN, TMS570LS1227

Hi,

I'm using TMS570LS1227 MCU and Halcogen 4.4.0.

In my project, I use the DCC1 module to verify OSCIN frequency, so I have selected:

- clock source 0: HF_LPO 10 MHz or 9,6 MHz?

- clock source 1: VCLK      20 MHz (the source of VCLK is PLL1)

First problem: the HF_LPO frequency should be 9,6 MHz because I have selected the trim from OTP (as in SPNS192B document).

Second problem: the HF_LPO trimmed frequency can change from 8 MHz to 11 MHz, with an error of 15% about.  So in DCC1 module, Should I set the clock drift to 15%? If so, the HF_LPO frequency cannot bet used to compare it to another.

Thanks

Enrico

  • 0
    TI__Guru**** 191886 points
    HI Enrico,
    There is a similar post asking the same question perhaps from your colleague. It has been answered. Please see below link to that post.
    e2e.ti.com/.../494120
  • 0 in reply to Charles Tsai
    Intellectual 695 points

    Hi,

    Yes, this post is similar but it isn't the same posted. I asked different questions.

    Best regards,

    Enrico

  • 0
    TI__Mastermind 20200 points

    Enrico,

    The trimmed frequency range extends from 8MHz to 11MHz. Therefore, if you are using this frequency as a reference for another clock, you DO need to allow this tolerance in the measurement. I agree that using the HF LPO is probably not a good reference clock for the DCC in terms of frequency accuracy.

    One thing to think about is that the CLKDET currently implements a wide frequency check on the oscillator. This module effectively ensures that the oscillator is still running. If the oscillator IS running, it is the most accurate clock in your system and can be used to measure other frequencies with higher accuracy than the HF LPO.

    Best Regards,

    Kevin Lavery