purpose of ckopt fuse

Go To Last Post
4 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hello:
ATTINY26 Application --external crystal, 10MHz

What is the purpose of the CKOPT fuse?!?...it seems to increase the external crystal drive level (which I need to have so I can drive a buffer clock gate from the crystal).

However I can find no info/specs on this feature.

Also in many places the manual says when NOT to set it, but not when TO set it. Am I getting in trouble by setting it? It seems to be working fine & my logic buffer is happy too.

Hoyt

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

At hi freqs, it increases rf emissions, and uses more juice, so they let you turn it off if you flunk the rf test

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I guess if you are driving more than one micro off the clock you may want to turn it on....I have never had to use it and I keep it off.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Actually the CKOPT fuse is used as a Selection for the capacitive impedence match at higher frequencies. As "Bob" says Atmel has provided this to reduce the RF noise that is produced when the clock line is not matched terminated. I too have used this principal to generate a RF modulating pulse output for my Mixer stages to the final Antenne.

AVR Rulez...;-)

Warm Regards,
Boseji
http://m8051.blogspot.com/