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Overclocking SX52 — Parallax Forums

Overclocking SX52

ElectronegativityElectronegativity Posts: 311
edited 2006-02-24 20:39 in General Discussion
I just ordered a couple of SX52 protoboards and was thinking of trying to get them to talk to the new Propeller chips (when they come out).

It would be nice to have them both run off the same clock.

Do you think I can get away with clocking the SX52 at 80MHz?

Is there a problem with having multiple MCU's run off the same clock?

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I wonder if this wire is hot...

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-02-24 18:11
    The XGS game system is run at 80MHz, it has a heatsink attached, you may want to do the same.

    You wouldn't be able to clock both off of the clock, because the propeller has an internal PLL which takes a 5MHz crystal and speeds it up 16x.

    You could theoretically take an active oscillator, feed it into both the Propeller XIN pin·and the SX OSC1 pin, then set the Propeller PLL to 1x.

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    ·1+1=10

    Post Edited (Paul Baker) : 2/24/2006 6:15:56 PM GMT
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2006-02-24 18:54
    Can you live with 75 MHz -- we had special osciallators made and they'll fit right into the demo board:

    http://www.parallax.com/detail.asp?product_id=252-00005

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    Jon Williams
    Applications Engineer, Parallax
  • ElectronegativityElectronegativity Posts: 311
    edited 2006-02-24 20:39
    75 Mhz would be fine but it seems like it would be a nightmare to synchronize two processors running at different speeds.

    75 MHz would be fine, but the real issue is synchronization.

    This all came as a result of trying to figure out the fastest way to get data in and out of the Propeller.

    A 4M SRAM has an 8 bit parallel interface and requires 19 more pins for addressing, plus a few more pins to set the read/write state and clock. Since the Propeller only has 32 I/O pins I was thinking that I could use the SX52 to provide the address and other information while hooking up the 8 data lines to the propeller.

    That would let me move data in and out quickly and still have 24 configurable pins.

    I suppose I could try to come up with some kind of asynchronous handshaking protocol, but life would be golden and wonderful if I could synchronize both MPUs.

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    I wonder if this wire is hot...
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