AVR External Crystal Waveform

[cksa]

What is a properly working external crystal on an avr suppose to look like? In terms of its waveform?

On one of my XTAL pins, the voltage is at 0.8v and the other is a sinewave swinging from 0.8 to 2.8v.  My power supply is at 2.8v

Just wondering if that is ok, or is the crystal signal supposed to swing from rail to rail.

Thanks.

[mikeselectricstuff]

The AVR has some config fuses to set the xtal drive power - 'full swing' and a frequency-specific range. The latter has advantages in reducing power draw.
A good rule is that a  'happy' oscillator has similar signal amplitudes on each pin, but you need to use a low-capacitance scope probe, e.g. x100 to avoid loading affecting the oscillator. A series 10M resistor on a normal x10 probe is an OK method if you don't have a x100 probe.