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    @el_supremo: I edited your code to remove the...

    @el_supremo: I edited your code to remove the '82' and substituted 'data_length' instead, with 'int data_length' as the second parameter in the crc14 wrapper function. That meant I could then pass my...
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    Good work, Frank. (...for other readers DARC...

    Good work, Frank. (...for other readers DARC means DAta Radio Channel).

    In addition to LORAN, the Russians are said to have same Eurofix data encoding (hope its not cyrillic :o) with a system...
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    I noticed a tiny glitch in your wrapper function...

    I noticed a tiny glitch in your wrapper function in post #2, in case anyone copies it verbatim.

    You have left a fixed integer of '82' in your call to crc_gen_bits, instead of using the "length"...
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    Frank, Pete - thanks very much for your interest...

    Frank, Pete - thanks very much for your interest and help. I'll tell you what I know so far. I'm on a steep learning curve...

    Each Eurofix "Message" format is 210 bits long - that's 30 times 7 bit...
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    Great stuff Pete. Will give it a try asap. Thanks...

    Great stuff Pete. Will give it a try asap. Thanks too Frank - I will look at your work on FastCRC to see if I can mod for CRC14.

    I'm back working on LORAN C (eLORAN) to decode the Loran Data...
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    Teensy CRC Generator/Checker

    Looking in the Freescale reference manuals, I spotted that the various chips have hardware CRC generation/checking capability.

    I'm looking to test 14 bit CRCs from a radio experiment. I notice...
  7. I seem to remember this does work, but it was...

    I seem to remember this does work, but it was some time ago that I tried it. I think I disabled the clock selection first before changing MOD, and re-enabled it after. There is a note in para 36.3.5...
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    Not the first time - I copied this code from...

    Not the first time - I copied this code from elsewhere (can't remember where), which was an example of threshold of a small 200 mV peak 10 MHz signal.

    I'm only working at 100 KHz. Here is my...
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    Finally, here is an interesting application of...

    Finally, here is an interesting application of the Teensy 3.5 comparator (CMP1). Its the detection of a LORAN C radio signal (see my previous work elsewhere in the forum). This signal is brief bursts...
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    GOOD NEWS to report this morning... in fact,...

    GOOD NEWS to report this morning... in fact, EXCELLENT NEWS as it turns out...

    Bad "Grounding" WAS the cause of trouble. Both boards now perform the same, and in fact exceedingly well, far better...
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    A few hours later. Have now done some tests on...

    A few hours later. Have now done some tests on the second Teensy 3.5 board.

    Hmm... not quite straightforward. Put it into the same breadboard circuit as the first one, and at first showing it was...
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    I'm afraid to report BAD NEWS... (using CMP1 and...

    I'm afraid to report BAD NEWS... (using CMP1 and not CMP0 here, so Pin 23 instead of Pin 11)...

    (1) I did a simple experiment first on CMP1. I put a 10 turn 10K pot across 3.3v and GND and fed the...
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    Teensy 3.5 5v tolerant for CMP

    I would like to experiment with the Teensy 3.5 comparators.

    I know that Teensy 3.5 has 5 volt tolerance on digital pins. Does this also apply if I map a comparator input to for example Port C6...
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    Mixing GHz signals

    A simple demonstration here showing the result of mixing two GHz signals together. One is 3.001 GHz and the other is 3.000 GHz. It follows on from my earlier experiments using a Teensy 3.1 to control...
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    Excellent idea... here is the 27th harmonic (one...

    Excellent idea... here is the 27th harmonic (one down).

    16389

    A little more informative. The symmetry is still not centred on the 27th exact frequency. And the display is not static, the base...
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    GPS Frequency Output surprise

    The ability to lock a frequency signal to accurate GPS timing is very useful for a number of Teensy projects. It may come as a bit of a surprise therefore to learn that the frequency signal from a...
  17. If you are trying to match the frequency (or...

    If you are trying to match the frequency (or subharmonic) of a NEO6 with a DDS type oscillator, you might do this without changing the crystal.

    The crystal can be considered as a "relative"...
  18. You might be interested to read this thread......

    You might be interested to read this thread... https://forum.pjrc.com/threads/35397-Teensy3-1-as-a-precision-Frequency-Standard
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    Experiment (4) – Test with two 1 GHz Dipole...

    Experiment (4) – Test with two 1 GHz Dipole Antennas (Transmit and Receive)

    In this fourth experiment, I illustrate radio signals transmitted from the ADF4351 via 50 ohm RG316 coax fed into a...
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    Experiment (3) – Making a 1 GHz Frequency Counter...

    Experiment (3) – Making a 1 GHz Frequency Counter

    In the last experiment, I measured the wavelength of a 1 GHz signal. Now it is time to actually count every individual cycle – all 1 billion per...
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    Experiment (2) – Measure 1 GHz wavelength...

    Experiment (2) – Measure 1 GHz wavelength [Analogue method]

    Haven’t got an amplitude modulation experiment ready yet, but here is one that can measure the wavelength of the ADF4351 1 GHz output...
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    The code I use for the ADF4351 control is listed...

    The code I use for the ADF4351 control is listed below. I use a Teensy 3.1 via the SPI bus but other Teensy boards should work. Note in the code that I shift the SPI Clock pin from pin 13 to pin 14....
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    Fun with GHz signals

    There are some impressive PCBs on the market these days. Various low cost “copy” Evaluation Boards in particular offer tremendous functionality. I was therefore delighted recently to stumble across...
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    Your original question is interesting. I wondered...

    Your original question is interesting. I wondered if the value for T3.5 is an error (I expected it to be similar to T3.6).

    I looked here https://www.nxp.com/docs/en/data-sheet/K66P144M180SF5V2.pdf...
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    I first thought your input was analogue...

    I first thought your input was analogue "acquisition" (to the ADC). But on reflection, it's not clear what "data" you wish to acquire - it could be digital? At HF frequencies, the zener protection...
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    It seems simple enough (using Ohms law). But...

    It seems simple enough (using Ohms law). But there are a few design decisions to be made - and that makes it more interesting.

    Is 80 volts the maximum? Or might this be variable even up to a peak...
  27. From your info, I think this is working as...

    From your info, I think this is working as intended. Its probably the best in the circumstances.

    I would suggest you add a heat sink to Q1 just to keep it a little cooler. When you add the...
  28. Sadly, you are reading it wrong. The value 0.05...

    Sadly, you are reading it wrong. The value 0.05 ohms refers to the Q1 MOSFET itself - the resistance between Source and Drain when it is operating.

    Try this with a digital voltmeter. Make three...
  29. That's a much better diagram :-). The data...

    That's a much better diagram :-).

    The data sheet for the Q1 P-ch 2JS334 shows the Source/Drain resistance to be around 0.05 ohms with a Gate voltage of -4 volts (Gate wrt Source). So when Q2 gets...
  30. For clarification... Paragraph 5 should read...

    For clarification...

    Paragraph 5 should read "...which changes your circuit and puts one side of the R2 10K on the power supply +5v with the other side on the GATE of Q1 and the DRAIN of Q2."
  31. First a little theory... NPN and PNP are terms...

    First a little theory... NPN and PNP are terms used only for Bipolar transistors. That's those with Emitter, Base and Collector terminals. When describing MOSFETs, the terms are N-channel and...
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    I see your point. Interestingly, I connected the...

    I see your point. Interestingly, I connected the Teensy output directly to the scope BNC (with about 4cm of direct wire), thereby removing the scope probe and leads from the setup. I got a seemingly...
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    The pulse interval is around 5.3 uSec (189 KHz)...

    The pulse interval is around 5.3 uSec (189 KHz) but a little shaky because the trigger level depends on ambient temperature (thermal energy of an atom being stripped to start the cascade)...

    14763...
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    Yes, you read that correctly - "+130 volts". It...

    Yes, you read that correctly - "+130 volts". It doesn't work with a lower rail at +120 volts (at least with my transistor).

    What the circuit relies on is stripping an electron out of the valence...
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    To find a comparison, I made the following...

    To find a comparison, I made the following breadboard circuit and found that it gave a very similar 5 nS pulse shape to T3.6...

    14751 14752

    I now suspect that the actual risetime is...
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    And in case you were wondering about T3.6 (at 240...

    And in case you were wondering about T3.6 (at 240 MHz overclock)...

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    The limit here is my scope leads bandwidth.
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    Rootin Tootin Fast Pulse Shootin

    Playing with the Teensy 3.2 today, I wondered what would be the fastest output pulse that I could generate.

    Using "120 MHz overclock" and initialising with "pinModeFast(23, OUTPUT)", the following...
  38. Its an interesting problem to count very high...

    Its an interesting problem to count very high speed pulses, such as photon arrival at a photomultiplier tube. I have just been reading the MC10E137 chip spec (PLCC-28 device).

    This is a very high...
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    Kris, are you trying to charge 12v batteries - or...

    Kris, are you trying to charge 12v batteries - or 6 volt batteries - or some other value? Are you charging these one by one or in a series or parallel combo? For a good solution, it is important to...
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    Something odd... How is a Teensy PWM pin driving...

    Something odd... How is a Teensy PWM pin driving a P-Channel FET even at 500 Hz from +15 volts? Can Kris show the circuit he currently uses (pen and paper and digital photo). Also, what is this...
  41. I'd be tempted to breadboard this circuit first...

    I'd be tempted to breadboard this circuit first for a test run. Use the +5v supply for the chip Vcc.

    14705

    Its got the right ratio for 3v3 down to 0v7, and I don't think fast edges will upset...
  42. Take a look at this spec for VGA -...

    Take a look at this spec for VGA - http://www.javiervalcarce.eu/html/vga-signal-format-timming-specs-en.html.

    Although the sync signals can be 0 volts to either +3v3 or +5v0, the RGB should only...
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    Suggestion - pinModeFast

    I came across the function "pinModeFast" recently (https://forum.pjrc.com/threads/28735-Interrupts-not-always-served-on-Teensy-3-1?p=75044&viewfull=1#post75044) and would love to see this as a...
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    One general purpose 4 pin device is PC123...

    One general purpose 4 pin device is PC123 (http://www.sharp-world.com/products/device/lineup/data/pdf/datasheet/PC123XxYSZ1B_e.pdf). Cheap on ebay if you look around. They have an isolation voltage...
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    Some more info and progress... I wired these...

    Some more info and progress...

    I wired these magnetometer boards to Teensy 3.1 via one metre length of ribbon cable with the pullups at the Teensy end. The purpose of the ribbon cable was to...
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    After further reading a bit of the I2C protocol,...

    After further reading a bit of the I2C protocol, the answer to Question 2 is that this is part of the basic operation. Seven bits of address are followed by an 8th bit as "0"/"1" for write/read...
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    Magnetometer QMC5883L problem

    I bought a couple of magnetometer boards from eBay recently and today attempted to get them working with a Teensy 3.1. These came from China and claimed to be HMC5883L. They also have a marking...
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    On the receiver (top diagram), the chip is being...

    On the receiver (top diagram), the chip is being supplied by 5v (called Vcc). So the output may rise to 5 volts. That's outside the compatibility for some Teensy types (ought to be 3v3). So the 47K...
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    Systick ISR

    Can anyone point me to the Teensy 3.1 core folder/file where the systick_isr is defined? I have looked without success.

    Should I wish to replace it with my own version, how would I "undefine" the...
  50. The main concern in this area - is safety. Bio...

    The main concern in this area - is safety. Bio Med products must "fail safe" if they are used as treatment. An old engineer would ask what failure conditions might be experienced. Logic can fail...
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