sharing a crystal

hinv

Is it possible to have 1 prop ringing a 5-6MHz crystal like normal, and another one just taking xin from the others xin?
If so, how many props could hang off an xin without loading down the signal too much?

Thanks,
Doug

Ale

You will connect the XO of the crystallized prop to the xi of the crystal-less one. I do not know how many you can drive though. But you can use a 1 gate ic as buffer.

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Leon

I'd use an oscillator module for several chips using the same clock. Using one crystal will probably add too much capacitance.

Leon

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Phil Pilgrim (PhiPi)

You can also use a counter output to drive the other Prop's Xin, if you don't mind sparing an I/O pin.

-Phil

Bill Henning

I tried this, and only had partial success - the "slave" propeller was unable to generate a VGA signal my monitor could lock to :-( otherwise it seemed to work, at the right frequency (measured by XINPUT+PLL16x, fed by a 5MHz square wave, and timing a blinking LED with a 10s cycle.)

Phil Pilgrim (PhiPi) said...
You can also use a counter output to drive the other Prop's Xin, if you don't mind sparing an I/O pin.

-Phil

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Largos - a nano operating system for the Propeller
www.mikronauts.com - a new blog about microcontrollers

Phil Pilgrim (PhiPi)

Bill,

When you tried that, did you use _CLKMODE = XINPUT + PLL16X on the slave device?

-Phil

Bill Henning

Yep. And I tried several different counter modes as well. No joy on VGA,

Phil Pilgrim (PhiPi) said...
Bill,

When you tried that, did you use _CLKMODE = XINPUT + PLL16X on the slave device?

-Phil

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Largos - a nano operating system for the Propeller
www.mikronauts.com - a new blog about microcontrollers