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  1. Seems that Post #2 is the situation.

    Seems that Post #2 is the situation.
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    A Teensy from 1969

    With this week being the 50th anniversary of the Moon Landings, I thought I would share a picture of the "Teensy" I was using that same year. It was just over 12 inches long and 2 inches wide. But...
  3. Bare Bones Sketch

    Let the board cool down. Remove any SD Card or other attachments. Then attach to the USB socket and try running the attached "Bare Bones" sketch on your T3.6.

    It will flash the LED four times...
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    Re post #3691 on GPT2 Compare behaviour, once the...

    Re post #3691 on GPT2 Compare behaviour, once the "penny" has dropped, then the design implemented becomes much more comprehensible.

    The three Compare channels are not completely independant in...
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    Thankyou for your diligence, and well spotted on...

    Thankyou for your diligence, and well spotted on the comment 51.1.1 and 51.1.2. I had missed that.

    Looks like you are correct - it is a "feature". On the diagram of Fig 51-1, it too shows a line...
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    Here is a sketch which illustrates the quirky...

    Here is a sketch which illustrates the quirky behaviour of GPT2 Compare3 and Compare2.

    Notice that it is only GPT2_OCR1 that determines the period/frequency of the output sq wave on a scope.
    ...
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    ... And by the way, the value you need to put...

    ... And by the way, the value you need to put into "Compare 3" OCR3 or "Compare 2" OCR2 to get the square wave appear must be less than or equal to the value that you put into "Compare 1" OCR1. You...
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    Update on Red Alert #3662...

    I have done a lot of tests today. There is something VERY ODD about GPT2. I think its a design fault in the chip itself (either that or I am not understanding the way it is supposed to work).

    I...
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    Thanks for the tip. I will try that. The...

    Thanks for the tip. I will try that.

    The reason I'm suspicious that something has changed is that I have - so far - been unable to "go backwards" and undo the mux that switched on the 150 MHz....
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    Red alert !!

    I have suspicions tonight that my experiments with turning on 150 MHz for GPT timers may have damaged the chip internally. Until I can clarify this further, please will all beta users refrain from...
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    @Manitou - Tried "DSB" and it made no difference....

    @Manitou - Tried "DSB" and it made no difference. If I can summarize, using GPT2 it looks like this... If you only enable Compare2 using "GPT2_IR = 0x00000002;" then it ONLY WORKS (the ISR) if you...
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    I have not used "DSB", but will give it a try....

    I have not used "DSB", but will give it a try. Thanks for your reference - useful to see how someone else does it.

    I think the Compare1, 2 and 3 are completely independant of each other in their...
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    GPT Timer Interrupt Behaviour

    Interesting experience whilst experimenting with GPT1 and GPT2 today. Using the 150 MHz clock, I wrote a simple test to use GPT1 Compare1 to generate an interrupt every second. In the ISR, I reset...
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    GPT timer clock selections

    @manitou - Yup, the RTC looks to be that little tin at the side of the reset button. Cute. I was mentally expecting a round long tin for RTC. Habits...

    The reason for lack of option 5 on GPT_CR...
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    150 MHz now available for GPT's

    Success now with 150 MHz peripheral clock available to GPT1 and GPT2, using bit 6 = 0 for CCM_CSCMR1[PRECLK_CLK_SEL]. I gated/stopped both GPT2 clocks CG13, CG12 of CCM_CCGR0, also GPT1 clocks...
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    Well, I've had one attempt to go for it... not...

    Well, I've had one attempt to go for it... not succeeded yet. May take a little to figure out why not. I discovered that clock gating registers can upset the IDE and monitor, but managed to recover...
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    @Paul - I'm still nervous about changing bit 6...

    @Paul - I'm still nervous about changing bit 6 which is CSCMR1[PERCLK_CLK_SEL]. I can disable the PIT module with MDIS and set GPTn_CR control modules to zero, but I'm concerned that other modules...
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    Playing with GPT1 and GPT2, I found that the...

    Playing with GPT1 and GPT2, I found that the highest clock speed available in the Clock selections (powerup de facto) to be 24 MHz. I'm trying to make 150 MHz available for counting. Reading the 1060...
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    @mjs513 - Thanks, it all helps. XBAR is a new...

    @mjs513 - Thanks, it all helps. XBAR is a new area for me.

    Just reading the 1060 RM XBAR chapters, there is an intriguing statement 60.2.1 that "...any input (typically FROM external GPIO pin or...
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    Thanks both for assistance and patience with my...

    Thanks both for assistance and patience with my dumbness. That IOMUX chapter is cavenous. Big change from the T3 world on muxing. Example sketches with plenty comment lines are going to be essential...
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    So many Timers, its a job knowing where to start....

    So many Timers, its a job knowing where to start. I'll experiment with them all and probe the features. Maybe make a writeup later to help T4 newcomers like myself.

    I notice that GPT are 32 bits...
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    Just received a T4 Beta2. Can someone please...

    Just received a T4 Beta2. Can someone please point me at a post for the latest beta2 external pin ALT mappings? Thanks - not easy trawling through 141 pages of posts. (Imagine these pins will be in...
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    24 Mhz Osc Control

    I have scanned through the 1050 ref manual, but cannot see any "digital capacitors" to adjust/nudge ppm of the 24 MHz Osc frequency. Does anyone know different? The Osc diagram shows external...
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    Just performed another test string longhand... ...

    Just performed another test string longhand...


    unsigned char TestData1[] = {0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38};

    The paper answer in 14 bit binary was "01 1010 0010 0010". Expressed as...
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    I'm finding the 7 bit and 14 bit worlds very...

    I'm finding the 7 bit and 14 bit worlds very cranky. Suddenly realised why I can't see any patterns in my Loran data... the Eurofix message structure is out of placement sync with the data when...
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    Does "augmented" mean that you simply place the...

    Does "augmented" mean that you simply place the CRC first, before the message, when doing a longhand division by the polynomial (at the receiver)? Would you also agree that the "To compensate..."...
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    I notice that your printed CRC14's have some...

    I notice that your printed CRC14's have some values in excess of 14 bits. That cannot be right for a CRC based on 14 bit calculations? Methinks, the CRC cannot be a remainder if it is bigger than 14...
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    Timing of FastCRC... on my scope, it took 3.4...

    Timing of FastCRC... on my scope, it took 3.4 uSec to perform the CRC14.eloran call plus one DigitalWriteFast statement. That's a T3.5 running @180 MHz (and a very precise 180 MHz I might add, since...
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    Frank, Pete Using a T3.5, I made a test of...

    Frank, Pete

    Using a T3.5, I made a test of CRC14.eloran just now and it worked brilliantly. The 56 bit test data was... uint8_t buf[] = {0xAA,0xAA,0xAA,0xAA,0xAA,0xAA,0xAA}; and this gave the...
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    @FrankB: Excellent news with 0x18,0x18,0x18 and...

    @FrankB: Excellent news with 0x18,0x18,0x18 and the result 0x01D5. I don't have another verified (longhand) test string yet, but will make one later (busy all day today).

    The naming should reflect...
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    Yes, that solved the issue. Thanks for your...

    Yes, that solved the issue. Thanks for your patience.

    I note that you have a different polynomial to 0x60B1, so I will alter that when I do some tests. Going to try the same one as in #15 with...
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    Apologies. Can't get your example to compile....

    Apologies. Can't get your example to compile. Keep getting "FastCRC14 does not name a type". Tried copying from github and putting 8 hours FastCRC.h in my program folder. Tried "Add File..." with a...
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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...
  39. 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...
  49. 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"...
  50. 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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