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MSP430G2153 XT1 oscillator and MCLK setting

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Replies: 5

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Hello,

I have a question about MSP430G2153 XT1 oscillator and MCLK setting.

The system is:

32768Hz oscillator is connected to MSP430G2153 XT1 pin.

And,I would like to use (for example) 8MHz MCLK by multiplying XT1 clock,but MSP430G2153 doesn't have FLL.

Is there any way to multiplying XT1 clock  to around 8MHz on MSP430G2153 ?

Or,Is it impossible ?

I would appriciate if someone could reply to my question.

Regards,

Hiroyasu

  • The G2153 has no direct hardware support for an FLL.

    However, you can implement it in software, with the help of timers: Count how many MCLK ticks there are between two XT1 ticks. If there are too few or too many, adjust the DCO/modulator up or down.

  • In reply to Clemens Ladisch:

    Hello ,

    Thank you for your reply.

    I would like to know if I could "multiply" XT1 clock for MCLK or not.
    I would like to use XT1 clock ( the frequency is 32768 Hz) for the source of MCLK.
    Is it possible or not ?

    Regards,
    Hiroyasu
  • In reply to Hiroyasu Matsubara:

    Hi Hiroyasu,
    So you want to use a LF crystal on LFXT1 and source the MCLK with this clock at 8 MHz? Since there is no clock multiplier available, I think this will not work.

    There is just a divider available, so you can use a 8 MHz crystal and divide this frequency in case that you need a slower one. You can also use the DCO to source your MCLK at 8 MHz like Clemens suggested or you choose an 4xx/5xx device with FLL.

    Best regards,
    Tobias

  • In reply to Tobias Oschmann:

    The way Clemens described is the only way to have the DCO running as a multiple of your crystal. You have to implement the FLL yourself.


  • In reply to Dennis Eichmann:

    Hello Dennis,

    Thank you for your reply.

    I could understand.

    Regards,

    Hiroyasu

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