[En-Nut-Discussion] Removal of 32kHz crystal

Harald Kipp harald.kipp at egnite.de
Tue Oct 5 18:19:41 CEST 2004


Hi Lars,

when explicitly setting NUT_CPU_FREQ, the Nut/OS system timer
(timer/counter 0) will use the main crystal only.

I have no idea, why everyone removes this in his own design.
It costs nothing. Do you really need these two bloody port bits?

Without clock crystal, you need to recompile the system, if
you change the main clock. And the thread "Using Power Save
Modes with Ethernut..." offers another advantage, using
Ethernut with power save mode. Actually this had been the
initial idea for adding the crystal since Ethernut 0.9.
Unfortunately it had never been implemented.

Harald

At 12:10 05.10.2004 +0200, you wrote:
>Hi all,
>
>Can someone please point me to a document, or explain, what features in 
>NutOS that requires the 32kHz crystal. If I set DNUT_CPY_FREQ = 8000000, 
>is it still necesary to use the 32kHz crystal?
>
>I am designing my own board and plan to use the MCU's internal 8MHz clock. 
>It would be beneficial to the design if I can remove the 32kHz crystal.
>
>Regards,
>
>Lars A Andersson




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