In message <355A3B61.8BE2DEBB@vgernet.net>, Ken Pergola writes >Is the internal PIC oscillator circuit >designed for series or parallel resonance >mode crystals -- or both? > >I've quickly read the app-note but didn't >seem to find the answer to my question. > *All* crystals have both a series resonance mode and a parallel resonance mode, the circuit determines which one is used. If you see a load capacitance stated it means that the crystal will operate at the stated frequency in a parallel resonance oscillator circuit with that load capacitance. The resonant frequencies are quite close , and usually don't matter with microprocessor applications. Microprocessor oscillator circuits such as that employed in PICs use the crystal in parallel resonance mode. Leon -- Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.