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OSC1 device setting for SX48 — Parallax Forums

OSC1 device setting for SX48

BoxcarBoxcar Posts: 1
edited 2007-08-02 08:13 in General Discussion
I've been having an issue with loading of the oscillator1 line on SX48s. I am running several SX48s off the output of one clock chip (at 50mhz) and have selected OSCHS3 as the oscillator type in the DEVICE setting. The clock signal level drops significantly when multiple SX48s are connected. Would changing this setting to HS1 or HS2 reduce the loading on the OSC1 pin? Does anyone know what the internal configuration of the oscillator is for the different clock settings?

Comments

  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2007-08-02 08:13
    The SX 48 data sheet pecifies that for external clocks above 50 MHz, the oscillator setting should be OSCHS3, and the internal XTAL buffer should be disabled, i.e. bit 4, XTLBUF_EN in the FUSE register should be cleared.

    Try the DEVICE DRIVEOFF directive to see if this makes a difference. You may also try the DEVICE FEEDBACKOFF directive to de-activate the internal feedback resistor.

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