Alan? ...? ?Except for Hans' habit of omitting any loading capacitors to maximise output /stability? - but it leaves the frequency rather high
Not exactly... originally?I had 22pF capacitors from each side of the crystal to ground, on the AVR microcontrollers. I found that there were always a non-trivial percentage of?people?reporting that the unit didn't work, and it was found to be due to the crystal not oscillating; removing the capacitors always solved this problem. So I soon started leaving the capacitors out, which reduced the BOM by two capacitors and had no apparent ill-effect.?
I've left the capacitors out ever after, still with no ill-effect. The crystal tends, as you mentioned, to oscillate a little higher (a few kHz) than its nominal value. But even with the capacitors calibration is still needed. In all the kits we don't need the reference oscillator to be actually on frequency, we just need to know what the reference frequency is. So the capacitors still had no importance.
