[KEAN64] How to get bus clock10 MHz from external crystal 8 MHz while FLL multiplier value equals 1024

[mohammedaboelna]

Hello,

On board TRK-KEAZN64, I'd like to get 10 MHz Bus clock and system clock 32 MHz.

The issue is that i have FLL multiplier equals 1024 which supports frequency in terms of 4 MHz only.

However, I seek 10 MHz which is not available with this FLL.

I mean that if my FLL multiplier equals 1000, My issue would be solved.

Any help instead of searching for crystal 10 Mhz because it is so hard to find another crystal of the proper type with 10 MHz. Actually my used crystal is that one assigned for the OpenSDA controller. I got it from another board.

[kerryzhou]

Hi Mohammed Aboeinasr,

    Thank you for your cooperation.

   1. You can't use external 8Mhz to get 10Mhz bus clock.

     8Mhz external crystal will get 32Mhz core clock, then 16 Mhz bus clock.

    As you know, the FLL factor in KEAZN64 is fixed, it is 1024.

  

So, if you want to use the external crystal, you just can use 10Mhz, generate 20Mhz core, and 10Mhz bus clock.

2. Actually, you also can use the internal trimmed IRC to get the 10Mhz with your on board opensda debugger.

   You just need to trim the internal clock to 39.0625khz.

  Take KDS PE as an example:

I also attach my project for your reference.

Wish it helps  you!

If you still have question about it, please let me know!

Have a great day,
Kerry

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