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Precision clocking a propeller chip. — Parallax Forums

Precision clocking a propeller chip.

TCP71TCP71 Posts: 38
edited 2012-05-01 09:32 in Propeller 1
I am looking to use high precision 10Mhz TTL waveform to clock a propeller. I've always just used a 5mhz crystal to run the props previously. Is there any conditioning that the propeller provides when you use the crystal and is there a way to turn it off and simply use the TTL? Any and all Ideas welcome. Sorry if this has been covered before. My intent is to use the precision input to create a very stable 50Hz or 100Hz sine wave using a single cog. Can I just connect the 10Mhz signal to the XI input and what would the settings for the configuration register need to be?
Thank you.

Comments

  • jmgjmg Posts: 15,183
    edited 2012-04-30 14:41
    Datasheet : 4.11. CLK Register
    shows the 4 OscMode choices
  • AribaAriba Posts: 2,690
    edited 2012-04-30 16:02
    Your TTL oscillator must work with 3.3V. Connect the 10MHz output of the oscillator to the XI pin of the Prop and let the XO pin unconnected.
    Then set the Propeller clock-mode to: 
    _clkmode  = xinput + pll8x
  _xinfreq  = 10_000_000

    Andy
  • TCP71TCP71 Posts: 38
    edited 2012-05-01 09:32
    Thank you all.
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