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Type: Posts; User: jimlux

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    More interesting data. I have a 15 hour run on...

    More interesting data.
    I have a 15 hour run on the 5 teensys where I logged the temperature (measured by the on chip sensor) and the frequency. The attached plots show the frequency and temp vs...
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    Interesting idea Constantin had there of putting...

    Interesting idea Constantin had there of putting the 32kHz crystal on and using the difference to figure out the temperature.


    In any case, the crystal is probably an AT cut (since that's popular...
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    characterizing the performance of the teensy oscillator

    In this case, the FreqMeasure library uses the K20's FTM to latch a counter whenever the 1pps comes in, and then it's unloaded by a (timing non-critical) ISR.

    I was prompted to do this by a...
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    Oscillator performance on Teensy 3.1

    I've been running some tests with 5 Teensy 3.1s to measure the onboard oscillator performance. I have a FS725 Rubidium source which puts out a 1pps tick that I run to pin 3 on the Teensy, and running...
  5. Thread: Teensy Qt

    by jimlux
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    It would be very useful to have...

    <feature request> It would be very useful to have a feature where you can dump output (or output and input) to a file. Right now I copy paste from the Monitor window to a file, then save it. This...
  6. Probably.. Teensyduino 1.18 on the Mac (don't...

    Probably.. Teensyduino 1.18 on the Mac (don't know a good way to get the "as installed" version, but the dmg is from August 2014)

    Although... I was doing some tests on another Windows machine,...
  7. USB serial driver returns slightly different style output for Mac and Windows

    While I was making some cross-platform utilities in python, I discovered that the Teensy USB serial port identifies itself slightly differently on Windows 7 and Mac OSX 10.9 (Mavericks)
    using the...
  8. Serial Numbers, MAC, and device name on MacOSX

    An interesting MacOSX feature discovered with TyQT on a Mac.
    Normally, the serial number of the USB device winds up as the device name (e.g. /dev/cu.usb12345 corresponds to SNR=12345). However, I...
  9. Yes, indeed, it looks like it might work. I'll...

    Yes, indeed, it looks like it might work. I'll have to dig into it some more.
    Doing the math outside in batches is fine (actually, preferred).
  10. Yep.. looks like IRQ_PIT_CH0 is interrupt #68...

    Yep.. looks like IRQ_PIT_CH0 is interrupt #68 (assuming that timer0 uses PIT 0)

    the UART IRQ #s are 44-50 (IRQ_UART0_LON)

    then in mk20dx128.c it looks like:
    // default all interrupts to...
  11. Have to look at ADC library..

    Our two inputs are on A0 and A1, doing 16 bit conversions.. Originally, the software was coded for the Teensy 3.0, and the timing skew between the two was around 2 microseconds, which is fine for our...
  12. need to sample both A0 and A1, and DMA library...

    need to sample both A0 and A1, and DMA library (as of a year ago, when we coded this up) only runs one ADC.
    The ISR, including the arithmetic operations for a 2 stage CIC decimator, consumes about...
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    Teensy 3.1 helps save lives in Nepal

    You may have seen the news coverage of a prototype victim detection radar called FINDER from NASA Jet Propulsion Lab that detects the heartbeats of buried victims....
  14. relative interrupt priorities (Timer0 vs UART) - Teensy3.1

    I've got an application using Timer0 to fire an ISR that does an analogRead() at 50kHz. The Serial1,Serial2,Serial3 all use interrupts to service their FIFOs. Which one is higher in priority.. in...
  15. Thread: Teensy Qt

    by jimlux
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    124,182

    Sure enough, that works. Awesome.

    Sure enough, that works. Awesome.
  16. Thread: Teensy Qt

    by jimlux
    Replies
    432
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    124,182

    Just downloaded the Win and MacOSX versions of...

    Just downloaded the Win and MacOSX versions of TyQt.. Works great, but...
    A couple questions:

    1) the serial number seems to be derived from the low order 2 bytes of the MAC (what I expected).. on...
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    DMX512 uses a 5 pin XLR... those aren't as cheap...

    DMX512 uses a 5 pin XLR... those aren't as cheap as the much more common 3 pin. (but they are still pretty inexpensive.. but more than a couple holes for soldering wires<grin>)

    yeah, the opto...
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    isolated 485 or 422 interface?

    I'm looking for a cheap isolated RS485 or RS422 interface to connect to a teensy3.1 for prototyping.

    I've found some DMX512 shields for arduino, and DMX 512 is basically RS485 with an expensive...
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    synchronous serial interface

    I'm looking at implementing a clocked synchronous serial interface (e.g. where you receive RxClk and RxData from an external device) at rates from about 100 kbps to a megabit/second or so. No...
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    Per Paul's suggestion in December, you should...

    Per Paul's suggestion in December, you should probably be disabling interrupts around the manipulation of the flash.
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    the USB com port behavior under windows is quite...

    the USB com port behavior under windows is quite complex. there's a lot of interaction between various power saving modes and such as well. You may want to download the "devcon.exe" program from...
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    Thanks, Paul.. But I think I'm going to attack...

    Thanks, Paul..

    But I think I'm going to attack this by good old empiricism. There's only a few ways to code it (simply) in C, and all I want to do is know if there's something simple that makes...
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    I know how long the processor takes, my question...

    I know how long the processor takes, my question is more about "what instructions does the compiler emit"...

    for instance, what's the relative speed of:

    long ilong,qlong, rlong, slong;
    int...
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    There's some definite bugs in my test code. ...

    There's some definite bugs in my test code. Everything was declared as char, as opposed to int or long.. I'm fixing it all now, and initial results are that it runs about 20% slower
    1024 10109
    ...
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    Yes.. times in microseconds..for 1024 complex...

    Yes.. times in microseconds..for 1024 complex points. the time requried is a bit lower than N*log(N), probably because there's some fixed overhead that becomes a smaller part of the overall time.
    ...
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    FFT benchmarks on teensy3

    I ran some benchmarks on a teensy3 using a fairly simple fixed point FFT. The original routine used program memory for the sin table and a FIX_MPY routine to do scaled multiplies, but since the...
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    What I do to identify modules, in the face of...

    What I do to identify modules, in the face of varying USB ids, is read the MAC on the teensy3s using software that's already loaded into the teensy. This doesn't help if you're loading from scratch,...
  28. jumping to loader (e.g. "pushing the button on a teensy3")

    how do you put the teensy3 into "program load" mode without pushing the button?
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    Controlling multiple Teensy3s from one PC

    I'm building some hardware where I've got half a dozen teensy3s digitizing samples and doing some filtering, then shooting them out the USB (pseudo com port). Naturally, the COM port number changes...
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