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Overclocking the propellor? — Parallax Forums

Overclocking the propellor?

A.C. fishingA.C. fishing Posts: 262
edited 2007-03-05 21:41 in Propeller 1
Would it be possible to change the propellor's external clock?
What would be the maxium speed possible?
thanks,
ACfishing

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Somebody said...
-Never Underestimate the power of human stupidity.
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Comments

  • ForrestForrest Posts: 1,341
    edited 2007-03-04 01:00
    There's currently a third-party Propeller design that runs at 96 MHz www.parallax.com/propeller/tools.asp

    Until Parallax releases the Propeller data sheet, we won't know what the official maximum speed is.

    I don't think it's a fluke that all of Parallax's Propeller designs include a socketed crystal.
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-04 01:15
    Actually, Chip has done informal testing of the maximum speed of the Propeller. Apparently the flag registers (C and Z) are the first to get flakey. As Forrest mentioned, the DLP-PROP operates with a 96MHz clock and this value has some advantages when trying to output broadcast video since the channel separations are 6MHz and you can use a 6MHz crystal with a 16x PLL to get 96MHz. Search the Propeller forum for messages from Chip. He's posted some of his experience pushing the Propeller chip to extremes. I think they ran it refrigerated for one test (over 200MHz if I recall correctly).
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-03-04 03:35
    While the official maximum speed is 80 MHz,·spot tests show the room temperature failure point is 110-120 MHz; but it's not wize to be operating it at the very limit of it's operation. You could use a 6.5MHz crystal·to achieve 104MHz operation and increase the likelyhood any particular Propeller would work at the frequency, but·please be aware that we do not guarantee every Propeller will work at this frequency.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.

    Post Edited (Paul Baker (Parallax)) : 3/5/2007 9:50:43 PM GMT
  • DogPDogP Posts: 168
    edited 2007-03-05 21:41
    Yeah, I'm running mine at 104MHz w/ a 6.5MHz xtal. All three of my prop chips run fine at that speed, but I realize that's not guaranteed. When I was ordering parts from Mouser it just happened that the 5MHz xtal that I ordered was backordered... luckily I ordered a few others for experimenting.

    Pat
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