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sima2
sima2
Associate III
August 15, 2011
Question

Switch from HSE to HSI on failure of the HSE?

  • August 15, 2011
  • 1 reply
  • 543 views
Posted on August 15, 2011 at 13:50

Hello

I would like to switch from the HSE oscilator to the HSI oscilator if there is a failure of the HSE oscilator. How can I do that with preserved SYSCLK (64MHz)?

The HSI klock is divided på 2 så the PLL would need to be changed by a factor of 2.

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    1 reply

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 15, 2011
    Posted on August 15, 2011 at 14:32

    PLLXTPRE (RCC_CFGR) permits you to feed HSE/2 into the PLL.

    Although losing a synchronous clock, and switching a locked PLL to a different clock (even slightly), is a whole barrel of fun.

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