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Type: Posts; User: MattH

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  1. Replies
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    External analog mux

    Hello,

    Dumb question: Can I connect directly each drain pin of a quad SPDP switch such as the ADG774 to the analog pins of my Teensy3.2 ? I mean do I need any capacitor or pull up/down resistor ?...
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    Turtle9er, your schematic looks very neat but...

    Turtle9er, your schematic looks very neat but maybe a bit overkill for a fuel gauge. The presence of C7 for instance makes me think this was designed for a very accurate high sampling rate...
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    I had a look at the NPN transistors but I kind of...

    I had a look at the NPN transistors but I kind of have the same problem: choosing the right component.

    16276

    I have an extremely low collector current (that's the point I don't want to drain...
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    Interesting thought. Thanks

    Interesting thought. Thanks
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    choosing FET for fuel gauge

    Hello,

    I need to monitor the battery level on one of my project but I would like to move away from the simple voltage divider solution since it unnecessarily drains some current. I only need to...
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    Crystal clear, thanks ! As for a separate...

    Crystal clear, thanks !

    As for a separate power rail for digital and analog, do you think it is worth it if I am using force sensitive resistors (hence low frequency) for my analog application ? I...
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    what makes AGND "analog" ?

    Hello,

    I am looking at voltage regulators for a different project and I was trying to understand what exactly was AGND on my Teensy. Looking at the schematics it seems that there is only one power...
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    I also tested the FreeMemory function which I...

    I also tested the FreeMemory function which I included in a separate library to save some space in my code. It's very neat and seems to work (I got 60596 free RAM in an empty sketch and 59824 when I...
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    good point. I printed the end result (data[])...

    good point.

    I printed the end result (data[]) and I also sprinkled FreeRAM() throughout the code (I realised that dynamic memory usage was... dynamic). I ended up with a minimum free RAM of 59883...
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    Hey Jacob, That's much better, but it's weird...

    Hey Jacob,

    That's much better, but it's weird that CPU usage is higher @96MHz than 72... I whole thing twice (i.e. changing the clock speed up and down) and got exactly the same values.

    empty:...
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    **cpuload Empty : 96MHz -> 22.1% 72MHz ->...

    **cpuload

    Empty :
    96MHz -> 22.1%
    72MHz -> 29.2%
    48MHz -> 43.5%
    24MHz -> 85.7%

    Project :
    96MHz -> 38.4%
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    Thanks Jacob, Stupid question: where do I...

    Thanks Jacob,

    Stupid question: where do I insert my code ? Where "// do other useful stuff...." is or in the wastesometime method ? Obviously I need to add all the relevant stuff in the setup too....
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    RAM and CPU usage

    Hello,
    I was trying to see how much resources my small project was taking using this sketch:
    https://forum.pjrc.com/threads/31664-measure-your-teensy-3-x-cpu-and-ram-usage!
    I found another one...
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    You could try with d=random(min, max) instead of...

    You could try with d=random(min, max) instead of 0 (I let you decide which min and max are best), so that the MCU has to do the math every single time in your infinite loop.
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    You're all making very good points. My project...

    You're all making very good points.
    My project is rather simple. I did not make an extensive use of Teensy's libraries except for I2C and BLE which can be found for the vast majority of chips. I am...
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    Spot on ! I owe you the success of my POC...

    Spot on !

    I owe you the success of my POC prototype Paul. Thanks a million !
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    Very interesting article thanks GW ! Again I...

    Very interesting article thanks GW !
    Again I won't be the one doing it but I want to know the general principle of MCU firmware development and what sort of skillset I should be looking for. As I...
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    Too bad, I was about to go for another MCU, a low...

    Too bad, I was about to go for another MCU, a low power one such as the STM32 ;)

    Regardless, my question was more of a general one. What do you have to do programming-wise when you buy a chip...
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    Microcontroller from scratch

    Hi all,

    I have made a successful proof-of-concept prototype based on a Teensy3.2 (thanks Paul BTW). Now I would like to turn that into a pre-industrial minimum viable product. It is extremely...
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    Is there a way to read the state of an input...

    Is there a way to read the state of an input (i.e. enabled/disabled ?)
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    Good point, I should have mentioned that I was...

    Good point, I should have mentioned that I was using a Teensy 3.2

    It makes sense then if I was actually enabling the pins...
    What about Serial.end, is it worth it ?
    Any other tip to save juice ?...
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    Low power uses too much power...

    Hello,

    I was trying to reduce power consumption following the advice given here : https://www.pjrc.com/teensy/low_power.html
    so I implemented this :


    if (LOW_POWER_MODE) {
    Serial.end();...
  23. FYI this is the answer I got from "horsey": ...

    FYI this is the answer I got from "horsey":


    So it is a short... but why would one do that ?
  24. Am I reading the schematics wrong ? If you turn...

    Am I reading the schematics wrong ? If you turn the switch in position P$3 doesn't it create a short circuit ? Because it's connected to the GND and JP2 to +3.3V

    I think there is another mistake...
  25. There it is: 15556 The green led does not...

    There it is:

    15556

    The green led does not turn red. there are two different diodes however I should have seen the red one during charging.
    I fully charged a LiPoly then looked at the discharge...
  26. Yes I did. By the way there are three...

    Yes I did.

    By the way there are three rectangular pads (a big one close to the centre and two small ones between the big one and Vin through hole). Do you separate all three pads (cutting 2...
  27. weird behaviour with the LiPo battery charger add-on

    Hello,

    I recently bought the LiPo battery charger add-on from Pesky products but I am not 100% satisfied and I would like your opinion/advice.
    Everything is fine when the microswitch is on: The...
  28. Thanks a lot !

    Thanks a lot !
  29. Brilliant ! I'll go for a 220nF then. Any...

    Brilliant ! I'll go for a 220nF then.

    Any objection to use a capacitor network ? (I am already using a resistor network). "Complicated" is perhaps a misnomer, I mean bulky (I am trying to fit the...
  30. Great ! thanks. And do you think using a...

    Great ! thanks.

    And do you think using a capacitance is helpful when working with FRS ? Should I be worried about noise at all ? Obviously I don't want to make the circuit any more complicated...
  31. voltage divider for force sensitive resistor

    Hello,

    I would like to connect a few force sensitive resistors to my Teensy3.2. I am basically going to follow these instructions...
  32. Thanks XFer !

    Thanks XFer !
  33. Teensy Loader is unable to read my compiled sketch (r)

    Hi, I got this error message and it says "This error should never happen. Please report this to paul@pjrc.com, hopefully with enough information to reproduce the problem so it can be understood and...
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    Interesting point. Easily checked I replaced ...

    Interesting point. Easily checked I replaced

    int rawMin=5;
    int rawMax=700;
    by

    int rawMin=random(5, 700);
    int rawMax=random(5, 700);

    It is slightly slower: 8us
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    Well, I was in 10th grade "only" 25 years ago but...

    Well, I was in 10th grade "only" 25 years ago but Horner's method was still around. I guess I was too excited about using exotic functions (I am new to programming) and eager to write complex code...
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    @Thermingenieur: Impressive !!! and so simple......

    @Thermingenieur: Impressive !!! and so simple... c'est pour ça qu'il y a des ingénieurs !

    I get down to a single us ! How is that even possible ?! Great !






    const float A=0.042866;
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    I am not sure I am understanding that correctly: ...

    I am not sure I am understanding that correctly:
    Is it possible to programatically change the clock speed ? Is T3.6 clocked by default to its maximum 180MHz ?
    Cheers
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    Thanks defragster, I didn't know whether a...

    Thanks defragster,
    I didn't know whether a pointer could point to a const (thinking about it, there is no reason why not) that's why I left the "const" out of the script. Thanks for confirming it's...
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    As as do care about speed (I have 16 sensors and...

    As as do care about speed (I have 16 sensors and I am hoping to get real-time-ish measures) I tried some optimisation using my Teensy 3.2 (should be faster on the 3.6):
    -pre-declaring the constants...
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    Brilliant, it's working ! Thanks guys ! And...

    Brilliant, it's working ! Thanks guys !

    And big thumb up for your wonderful board Paul
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    Best way to do complex calculation ?

    Hi everyone,

    I am trying to apply a mathematical model (5th order polynomial) to a sensor output value on a Teensy3.6.
    I know there is only a 2-decimal precision and that the usual workaround is...
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