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  1. Hey it's only 5 years later, I'll try to fix some...

    Hey it's only 5 years later, I'll try to fix some damage... that code I posted in 2014 was for an apparently early/ nonstandard/ obsolete version of the EtherCard library. It was doing two different...
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    Looks great! I wasn't familiar with the Rabbit...

    Looks great! I wasn't familiar with the Rabbit RCM3200 so I looked it up. Don't tell Paul how much it costs, or he might raise the price of the Teensy :-)
  3. Well this is definitely a workaround (hack)...

    Well this is definitely a workaround (hack) rather than actually fixing whatever the problem really is. However, it has the cardinal virtue of just working.
    Basically, reset the USB device from the...
  4. Update: I have tried each of the suggested serial...

    Update: I have tried each of the suggested serial programs (minicom, picocom and screen). They all work in the same manner as my Python program, that is, they show the data coming from Teensy as...
  5. Thanks for the reply, I will try that. I have...

    Thanks for the reply, I will try that. I have since found that my Python program sometimes still does work after longer delays "off" on the Pi- but not always.
    There is apparently something "funny"...
  6. Teensy 3.2 with Raspberry Pi: USB stops working when ignored too long?

    This seems like a beginner question, I thought I'd passed that stage but apparently not!

    I have a Teensy 3.2 which prints one line of text (data from ADC) every half-second or so, using...
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    Teensy on Amazon?

    I had not previously noticed that Teensy 3.2 was sold on Amazon, for example: https://www.amazon.com/PJRC-6485230-Teensy-Original-Version/dp/B015M3K5NG/ the listing says "Teensy 3.2 (Original...
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    Curious if you find this ADS1256 chip...

    Curious if you find this ADS1256 chip occasionally resets when you didn't want it to. Among other things, the reset means it returns to its default of 30 kHz sampling rate, so that can be a problem...
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    If you care about precision, an old-fashioned...

    If you care about precision, an old-fashioned resistive divider can be made quite accurate if you use precision resistors, they don't notice ESD and are probably OK with brief overvoltage. I don't...
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    frequency offset vs. CPU temperature

    @mjs513 I don't know the best way to implement turning off the keeper. I think the default should be no keeper when a pin is used as analog input. I suppose there might be cases where you might...
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    You can use a built-in pullup or pulldown to keep...

    You can use a built-in pullup or pulldown to keep an input from floating near Vdd/2 where MOS gates have excess power dissipation. A "keeper" automatically switches between pullup or pulldown...
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    Yes! Thank you, I can confirm that adding this...

    Yes! Thank you, I can confirm that adding this line to my setup removed the glitch around count 2078 that I found earlier. Now when you look at the standard deviation along the curve you see only the...
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    ADC input question: is "keeper" GPIO enabled?

    Just accepted my invite to the T4 Beta1 testers and got the hardware; thanks Paul & Robin!

    I tried measuring a slowly changing voltage using the ADC A0 input. My voltage source was 4300 uF of...
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    Theoretically speaking, can you make an accurate...

    Theoretically speaking, can you make an accurate measure of risetime when you have only a very short pulse, rather than a step? I think it might require additional assumptions like single-pole...
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    3.8 ns pulse width, that's pretty fast! It...

    3.8 ns pulse width, that's pretty fast!
    It looks like Table 2.3.2 General switching specifications on p.18 of https://www.pjrc.com/teensy/K66P144M180SF5V2.pdf says the shortest guaranteed valid...
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    Pretty impressive! A while back I was playing...

    Pretty impressive! A while back I was playing around with pulses from a Raspberry Pi and only got about 10 nsec pulse width, and I was also not sure about the capability of the scope to fully...
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    It is very educational to experiment with things...

    It is very educational to experiment with things so I'm not arguing against that. If you want a near-term practical solution, you can buy adjustable CC-CV supplies (constant current / constant...
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    Look up "MOSFET Gate Driver", even really small...

    Look up "MOSFET Gate Driver", even really small ones like the SOT363 package Diodes Inc. ZXGD3009DYTA can deliver up to 2 amps peak current, a lot more than your typical 10s-of-mA drive that a GPIO...
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    NOTE: my original code block for pinModeFast is...

    NOTE: my original code block for pinModeFast is missing a close bracket } at the end, somehow missed it in a cut-and-paste, sorry about that!

    <edit>: added close bracket }
  20. anything like PulsePosition input but 2-channel relative timing?

    If I understand it correctly, the Pulse Position library uses a hardware timer to get 1 / (48 MHz) or 21 nsec resolution on the interval between two rising edges of a waveform, on a given input...
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    If the total data rate from the camera is within...

    If the total data rate from the camera is within what the Teensy USB link can deliver, then it's possible in theory. It seems an awful lot easier to simply use a USB hub, however. Then from the hub...
  22. Thread: fft ifft ?

    by JBeale
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    Just as a guess, in many practical engineering...

    Just as a guess, in many practical engineering applications of the FFT you really only care about the amplitude of the (real) power spectrum. You don't want the additional memory space and data...
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    ...or a separate regulator and a separate ground...

    ...or a separate regulator and a separate ground return for the SD card power supply.
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    As a point of reference, a few years ago I backed...

    As a point of reference, a few years ago I backed a Kickstarter for "Navspark" which included a 100MHz 32bit LEON3 Sparc-V8 + IEEE-754 Compliant FPU, 1024KB Flash Memory + 212KB RAM, ~80uA/MHz @...
  25. I'm curious whether it is possible to use the...

    I'm curious whether it is possible to use the phase modulation of WWVB, which I have read is supposed to allow for additional processing gain, eg. better performance on weak signals.

    There is a...
  26. I assume all this write-time variability comes...

    I assume all this write-time variability comes from some low-level physics in the individual storage cells (randomly some sticky / pinned states needing extra time to inject enough charge). If so,...
  27. Ah, ok the plastic bag serves to prevent direct...

    Ah, ok the plastic bag serves to prevent direct exposure. In my case I did not test before/after on the same element, but looking at the spectrogram output the higher frequencies were definitely...
  28. I am curious how that mic performs in outdoor...

    I am curious how that mic performs in outdoor 24/7 recording situations. I have previously done that kind of ambient recording using a sensitive electret mic claiming 80 dB-A SNR...
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    FWIW: apart from some brief development time, all...

    FWIW: apart from some brief development time, all my use cases for Teensy have been 24/7 type applications, for which I want to minimize the possibility that the device gets turned off by accident...
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    typo for MKR1000 ?...

    typo for MKR1000 ? https://store.arduino.cc/usa/arduino-mkr1000 this has a wifi module and also LiPo charging circuit
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    Just to be clear, is this the page you are...

    Just to be clear, is this the page you are talking about? https://www.pjrc.com/teensy/techspecs.html

    The way I understand the current situation is that the board does have the capability to run...
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    ah- it is because in your link there is no colon...

    ah- it is because in your link there is no colon : between the https and the //
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    Thanks, very useful! BTW the link you have for...

    Thanks, very useful! BTW the link you have for serialplot did not work for me but this does: https://bitbucket.org/hyOzd/serialplot
  34. One other note about sensitivity towards the...

    One other note about sensitivity towards the backside. It is actually quite difficult to shield microwaves 100% because even a very tiny gap or crack in your groundplane can act as a slot antenna and...
  35. measuring antenna pattern at 10 GHz

    By the way, about my antenna pattern, that was a project in itself. You need a detector of some kind. I tried an old HP X421A (8 - 12.4 GHz crystal detector on WR-90 waveguide flange) and also a...
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    This post starts with a complete code example...

    This post starts with a complete code example including the function you mention, so you could go from there....
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    I had a similar question, and was able to slow...

    I had a similar question, and was able to slow down the FFT sample rate for better frequency resolution as described in this thread:...
  38. On the simplest microcontrollers you can rely on...

    On the simplest microcontrollers you can rely on instruction cycle timing, but Teensy 3 is already complicated enough (esp. with DMA, as Paul mentioned) that time-critical operations are best done...
  39. > "...it would leave the micro-USB socket free in...

    > "...it would leave the micro-USB socket free in case I have to reload the script."
    Depending on the length of the wires, it is not guaranteed that the USB connection would work to reload the...
  40. I realize this is hopelessly late, but it is very...

    I realize this is hopelessly late, but it is very simple to work with fourier transforms (in practice, FFT) on a PC, using tools like Matlab. Here's an example...
  41. If the standard SD card stores 2 or 3 bits with a...

    If the standard SD card stores 2 or 3 bits with a single cell, I'd expect it to be 2 or 3x cheaper per GB than the SLC type (1 bit per cell). However that Panasonic part costs 10x more than the...
  42. How are you measuring the sample rate? If it is...

    How are you measuring the sample rate? If it is by counting the number of bytes transferred to your PC, that is not a very reliable method. The data transfer over a PC's USB port is interrupted by...
  43. I don't have a PDF of the new curved horn. It is...

    I don't have a PDF of the new curved horn. It is not dramatically curved. I just made a mockup pattern by eye out of paper (see photo), and then used that to cut it out of aluminum flashing from Home...
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    The code does not show us the full picture...

    The code does not show us the full picture without knowing how this photoresistor is connected. I assume this is a CdS or CdSn (cadmium sulfide / cadmium selenide) device.

    Normally you would make...
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    You can type "USB host" into the search box at...

    You can type "USB host" into the search box at upper right on this forum and see what people have done with this so far.
    I have not heard of any driver that would make this possible on Teensy as...
  46. another horn antenna

    I made another horn using aluminum flashing (thin sheetmetal) and aluminum HVAC tape, with a slight exponential curve (eg. flared instead of straight) and a rounded lip which reduces edge...
  47. Thanks for that info. I can confirm when I...

    Thanks for that info. I can confirm when I changed that in the library to naverage = 2, I did get back FFT256 results 2x faster than I did with the FFT1024 case, so it works as expected.
  48. Speed of FFT256? Expected 4x faster, but actually 2x slower than FFT1024

    I manually added the "volatile" fix to the Audio library analyze_fft256.h file. Now the 256 element FFT works.

    BUT I am puzzled by the fact that 100 cycles of the loop (code in my earlier post)...
  49. That was a lightning fast code fix! And I see...

    That was a lightning fast code fix! And I see Paul has already pulled it in. Thanks for the quick work. -john
  50. Hi Frank, Yes, I had a silly mistake on the...

    Hi Frank,

    Yes, I had a silly mistake on the index i instead of j. This is just example code anyway, but I fixed that (see below). The behavior the same: it prints out only 1 line with FFT256. I...
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