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Topic: 24Mhz High Precision Crystal Clock Oscillator (Read 3087 times) previous topic - next topic

Coding Badly

24 MHz is beyond the specifications.  Others have reported success over-clocking AVR processors but it is always a gamble.  It is your application so you will have to decide if it is worth the risk.


See section 8.2 of the ATMega328 datasheet for more discussion of the crystals to use.

See this note in particular from Tables 8-3 & 8-5.
"If the crystal frequency exceeds the specification of the device (depends on VCC), the CKDIV8
Fuse can be programmed in order to divide the internal frequency by 8. It must be ensured
that the resulting divided clock meets the frequency specification of the device."
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Coding Badly

Thanks for the post.  I assumed CKDIV8 only applied to the internal oscillator.


Nothing like making life difficult. Other than the technical implications of whether it will run at 24Mhz, it will introduce a lot of non-trivial timing issues, particularly with serial and uploading sketches. 

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