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Thread: Teensy 3.6 Overclocked to 256 MHz

  1. #1
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    Teensy 3.6 Overclocked to 256 MHz

    Paul and Frank,
    I thought I'd try out the 256 MHz overclock. It works a treat. Did a simple series of digitalWrites in a loop to track the speed improvement vs the clock speed increase

    Rough numbers for a digitalWrite HIGH/LOW cycle
    180 MHz ~ 167 ns
    192 MHz ~ 155 ns
    216 MHz ~ 138 ns
    240 MHz ~ 124 ns
    256 MHz ~ 117 ns

    Temperature is definitely rising as expected, but using an infrared thermometer isn't spotting anything unusual.

    The new clock speed will certainly be useful.
    Thanks for all the effort in getting this out to us.
    Bruce

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    Now try with digitalWriteFast(); and be still more amazed...

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    Senior Member+ Frank B's Avatar
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    The code can overclock F_BUS to 128MHz, too, so in some cases this will give a good speed-improvement too (I'm not 100% sure, but not in the GPIO-case , I think)
    This needs a special setting.
    Good night (00:18 here)

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    That's in the plan, but I didn't have time to hook up my 500 MHz scope. The times posted were measured using the Analog Duscovery 2 which is hooked up for day to day stuff

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    Senior Member PaulStoffregen's Avatar
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    Oh, I'm really curious to see how the waveforms really look when measured with 500 MHz bandwidth!

    Here's an old thread with the best I could do having only a 200 MHz scope.

    https://forum.pjrc.com/threads/41874...l=1#post132363

    The test program is on msg #18 of that thread. The direct pin config access is needed to put the pin in high speed mode, without the normal slew rate limiting.

    Even with 200 MHz, the spring clip and ground lead attached to the scope made a huge problem, when trying to measure the bursts of 120 MHz pulses.

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    Paul, it was that thread that prompted me to run the test I did today. I do want to repeat the test using digitalWriteFast;
    I'm curious about the pin speed on my "big gun" as well. At the moment the 3.6 is in a breadboard and to be honest I'm afraid to remove it after the difficulty of inserting it into the breadboard. Is there any danger of stress on the processor damaging the BGA solder joints if the board gets flexed?

  7. #7
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by Frank B View Post
    The code can overclock F_BUS to 128MHz, too, so in some cases this will give a good speed-improvement too (I'm not 100% sure, but not in the GPIO-case , I think)
    This needs a special setting.
    Good night (00:18 here)
    @Frank - just to confirm faster F_BUS gives faster updates to GPIO as noted on this thread Need-Faster-Interrupt-Handling!!

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