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Type: Posts; User: LarryP

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    A2D input impedance: c=.01uF difficult to achieve with a timeConst < 1 nanoSecond

    Greetings all,

    I've noticed something else puzzling re the K20's A2D and suggested circuit elements for best A2D results. I'm seeking any opinions/insights about this apparent strangeness:

    In...
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    K20's A2D impedance vs. Analog signal impedance

    Regarding The K20's A2D impedance and consequences for signal impedance:

    In Sect. 6.6.1 of http://cache.freescale.com/files/32bit/doc/data_sheet/K20P64M50SF0.pdf Table 24 gives us:
    R_ADIN...
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    Quadrature decoding: Clock source(s) and suggested default value for the filters

    Paul,

    Datasheet sect. 35.1.2 states:

    The FTM block diagram shows this as well. So it appears we have some flexibility re clock sources for encoder decoding.

    Regarding filtering for...
  4. Thanks for posting links to other docs with info on chip/chip differences.

    @Jp3141,

    Thanks much for the pointers to the other documents.

    FYI, from the links you provided, I found the following table to be the closest to what I was looking for:
    ...
  5. Seeking info on chip/chip differences re peripheral functions

    Greetings all,

    Please forgive me if I've missed something obvious, but I'm having some trouble understanding which peripherals are present in the specific chip used in Teensy3 and what pins they...
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    Some data on encoder frequencies from rotary encoders

    Paul,

    Regarding overflow/underflow/race-condition issues in encoder software:

    From my reading of the data (I have trouble calling a 1200+ page document a) sheet section, the chip designers...
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    Don't think analogWrite() precludes encoder reading. Just can't do both at once.

    @Jp3141,

    Thanks for your response; glad to see others interested.

    As I understand it, the existence of analogWrite (a flavor of PWM) for pins 3 or 4 shouldn't be a problem for encoder reading...
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    First notes toward hardware-based encoder decoding for the T3

    I took a first look at hardware-based encoder decoding on the T3. For what they're worth, here are my notes from scoping out hardware decoding.


    Don't look for encoder in the monstrous data...
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    @ZTiK.nl, Thank you for taking the time and...

    @ZTiK.nl,

    Thank you for taking the time and effort to put together your Teensy 3 MicroSD guide!
    Having that really helped me get my SD_Card working with a Teensy3. Should you ever find...
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    A quick look at body capacitance when body is floating electrically, approx 125 pF.

    Dave,

    I just did a quick look at how much capacitance increases when I touch a wire connected to a touchPin vs. when I don't touch it. If I'm remembering my physics, a conductor, even one not...
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    Modified files for touchReadTimeLim attached (I hope)

    If all goes well, the two modified files in the Arduino_1.0.3 and Paul's beta12 teensy3 software, namely touch.c and core_pins.h should be attached to this forum post. Also included is the Arduino...
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    Robin, Thanks for making those file types...

    Robin,

    Thanks for making those file types uploadable. I think that'll make it easier for people on this forum to help one another.

    Larry
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    touchReadTimeLim code, this time with formatting preserved

    Here are the three chunks of code for touchReadTimeLim -- this time with their indentation preserved. :)
    If you have any comments or corrections, please let me know.

    Thanks,

    Larry
    ...
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    @Darkness, First off, thanks for posting...

    @Darkness,

    First off, thanks for posting detailed data + the code that generated it!

    I've wrestled with several A2D systems (remember when those were entire boards?) in which the Mux,...
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    Cannot upload files for touchReadTimeLim

    Nuts, the forum software ate my code's indenting.

    @Paul,
    I tried to attach the files, but I'm getting invalid file type errors for .c, ,h and .ino files. Am I doing something wrong, or are...
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    A time bounded variant of touchRead()

    Greetings all,

    First off, I'm quite impressed with the resolution of touchRead measurements. 1/20 of a pF is way more sensitivity than I would have expected!

    Due to my control-systems...
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