Re: [avr-chat] Newbie fuse selection..attempt 2

[Graham Davies]

Ben Mann wrote: "A "series cut" crystal would not work ..."

This is not true.  It would just oscillate somewhat away from the nominal
frequency.  Also, there is no such thing as "series cut".  Ben is getting
"cut" mixed up with "resonant".

Richard Urwin wrote: "Someone pointed out to me a while ago that breadboard
has a built in
capacitance of 20pF or so. Adding XTAL capacitors may actually stop the
clock working."

This is also unlikely to be the problem.  A typical parallel-resonant
crystal is calibrated at a capacitance of 20 pF.  (Other common values are
18 pF and 30 pF.)  Such a crystal is designed to work with 20 pF between its
terminals.  If your breadboard has 20 pF stray capacitance between the
crystal terminals, which is possible with a careless layout, then adding the
22 pF capacitors to ground adds 11 pF giving 31 pF total.  This isn't going
to stop the clock.  Again, it will just oscillate a bit away from the
correct frequency.

Graham.