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Thread: Coming Soon: Teensy-LC (low cost Teensy)

  1. #526
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    On the first equation, it calls for an undefined C, T, and mV, two of which (C and mV) I input from sensor specs using an example temperature (C) of 10 degrees and corresponding (mV) of 980. The second equation mentions solving for T, so I went on with it using the same 980 mV. I got T=36 using my spreadsheet and T=1380.91 using the online equation site. I remember now why I hated algebra class so much.

    I saved both equations as JPGs I'll attach.

    Click image for larger version. 

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    EDIT
    I'm not sure how I missed it, but the TMP 36 appears to do everything I need it to do w/o all the complex math. The site says accuracy drops off above 125C, but I doubt my oil will hit 257F.
    Last edited by 2_Wheeler; 10-07-2016 at 10:04 PM. Reason: Change of plans

  2. #527
    Can Teensy LC be re-programmed with new code after using as usb midi controller with pc.???

  3. #528
    Senior Member+ Frank B's Avatar
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    Yes.......

  4. #529
    Thank u sir ,,, can i get direct link of all needed softwares for pc window 7(to make my own usb midi controller from teensy LC)
    Last edited by charnjit; 10-10-2016 at 12:32 PM.

  5. #530
    Please reply if any member from INDIA

  6. #531
    Senior Member Wozzy's Avatar
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    Quote Originally Posted by charnjit View Post
    can i get direct link of all needed softwares for pc
    http://www.pjrc.com/teensy/td_download.html

  7. #532
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    I'm fiddling with getting the LC working with the TLC5940 library, but so far my bit of hackery hasn't had any effect. The LC isn't officially supported by the library, but I assume that's just because the LC was released after the most recent update to the library and not because of some actual incompatibility. Before I dig too much deeper, does anybody know anything that would prevent the LC from working with this library the same as the 3.0/1/2?

    For reference: https://www.pjrc.com/teensy/td_libs_Tlc5940.html

  8. #533
    Senior Member+ MichaelMeissner's Avatar
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    Note, the LC uses an ARM Cortex M0, while the 3.0/3.1/3.2 use variants of the M4 (and the 3.5/3.6 use variants of the M4F). The library plays with the underlying timers, pin configurations, and pin interrupts. So, you will likely need to delve deep into the datasheet of both the LC and the 3.2.

  9. #534
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Omnigamer View Post
    The LC isn't officially supported by the library, but I assume that's just because the LC was released after the most recent update to the library
    By the time Teensy LC was released, that ancient TLC5940 had long become obsolete. Many better chips have replace it, and the need for PWM LED chips is much less now that WS2812B and APA102 addressable LEDs are so commom.

    and not because of some actual incompatibility.
    Teensy LC lacks the CMT timer peripheral which exists in all the Teensy 3.x boards.

  10. #535
    Senior Member PaulStoffregen's Avatar
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    You might look at ShiftPWM, using 74HCT595 chips and resistors. ShiftPWM was ported to Teensy LC.

  11. #536
    Senior Member Pensive's Avatar
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    Apologies if you read my post - it was related to the pca9685 not the TLC5940, therefore irrelevant and now deleted

  12. #537
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    My specific application requires constant-current all the time, so I was hoping to make use the DC mode on the TLC5940 rather than any of the PWM management. In the end I decided it was easier to write my own small library for interacting with it; works fine for the time being.

  13. #538
    I want to make a midi controller using teensy LC . I have also code for this . Teensy loader is installed on pc. In Arduino 1.6.12 ,there is not option to select teensy lc in board. There is also no option to select midi in Usb Type. So , please tell me which version of Arduino is correct to make midi controller from teensy lc board ? ,,,,,,,, can be made midi controller from teensy lc using c or c++ ? ,,,,,,,,,Please give me any solution

  14. #539
    Senior Member+ MichaelMeissner's Avatar
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    You have to install the Teensydunio overlay to Arduino 1.6.12 (http://www.pjrc.com/teensy/td_download.html). The Teensydunio installation is a lot more complex than the Arduino board overlay system can handle.

  15. #540
    2 push buttons are used to control 1 parameter in midi controller using teensy LC board.if I want connect only push buttons for maximum parameters. How many maximum buttons and how many maximum parameters can be control from teensy LC ?
    Last edited by charnjit; 11-09-2016 at 04:38 AM.

  16. #541
    Three Questions:

    #1. The two pin header holes marked 3.3v I assume get 3.3v output voltage from the VOUT33 pin on the processor. So these are not in any way used as input 3.3v to power the chip...correct?

    #2. Why would I need to cut the jumper between VUSB and VIN. If I cut it, won't I will always need Battery power at VIN...even when using a USB cable for flashing or in a user program that employs USB?

    #3. In applications where USB won't be used (no USB cable), we therefore need to power the board with 5v from an external source. What is the difference in powering externally through the VUSB header vs. the VIN header? I don't want to cut the jumper because I do want retain the option of powering the board solely off of a USB cable. But, if there is no USB cable present, I don't see any difference in powering externally from either VIN or VUSB. That's certainly what the schematic seems to show.

    The bottom line is:
    - if the board is being powered off a USB Cable, you should have 5 volts ouput power at both VUSB and VIN.
    - if there is no USB cable present you can power with 5volts at VUSB...and draw 5volts at VIN....or...you can power with 5volts at VIN...and draw 5volts at VUSB.
    Isn't that correct?
    Last edited by Burly; 11-11-2016 at 05:07 AM.

  17. #542
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by Burly View Post
    Three Questions:

    #1. The two pin header holes marked 3.3v I assume get 3.3v output voltage from the VOUT33 pin on the processor. So these are not in any way used as input 3.3v to power the chip...correct?
    Note, I'm a software guy, but.... You can power the Teensy through the 3.3v pins providing you have no power on the VIN pin (and VUSB if it is connected to VIN). As I understand it, USB won't work (if the VIN->VUSB solder pad is cut), because it needs 5v.

    Quote Originally Posted by Burly View Post
    #2. Why would I need to cut the jumper between VUSB and VIN. If I cut it, won't I will always need Battery power at VIN...even when using a USB cable for flashing or in a user program that employs USB?
    You might want to cut the connection if you are powering the Teensy by feeding it power through VIN. For example, you might need more watts than a typical USB connection might make. Or perhaps you have a lipo battery that powers the Teensy, and uses the 5v from VUSB to recharge the battery (for example, https://www.tindie.com/products/oneh...ttery-charger/). Yes, if you cut the VUSB/VIN solder pad, you will need to provide appropriate voltage to VIN to power the Teensy when doing a download.

    Quote Originally Posted by Burly View Post
    #3. In applications where USB won't be used (no USB cable), we therefore need to power the board with 5v from an external source. What is the difference in powering externally through the VUSB header vs. the VIN header? I don't want to cut the jumper because I do want retain the option of powering the board solely off of a USB cable. But, if there is no USB cable present, I don't see any difference in powering externally from either VIN or VUSB. That's certainly what the schematic seems to show.

    The bottom line is:
    - if the board is being powered off a USB Cable, you should have 5 volts ouput power at both VUSB and VIN.
    - if there is no USB cable present you can power with 5volts at VUSB...and draw 5volts at VIN....or...you can power with 5volts at VIN...and draw 5volts at VUSB.
    Isn't that correct?
    In general, things are simpler if have power coming from only one source. If it comes from two sources without something like diodes to block the power going backwards, whichever power source is weaker will have current coming in from the strong source. As I said, you can use diodes to make the power go in one direction, but diodes take power also. Or you can do like I do, and just only plug in one source at a time.

  18. #543
    Hi Michael,

    I totally agree about only having one source of power.
    And I don't want to loose the ability to power strictly off of USB...so cutting the jumper is a non-starter.

    I want to either be pulling power off the USB cable if one is plugged in.
    Or, I want to be sourcing 5v externally when the USB cable is not present.
    And in this case there is no battery charging involved.

    But I'm still scratching my head over the schematic.

    I'm spinning a new Base Board that will use the Teensy LC as a Riser Board.
    When the USB cable is not present, I want to power with an external 5v source, by going in through the VUSB header.
    It's much more convenient from a layout perspective than going through the VIN header.
    I can't see where it would be an issue.
    Last edited by Burly; 11-11-2016 at 06:42 AM.

  19. #544
    VUSB and VIN are one and the same if the trace/jumper is not cut. You can supply 5V through either header to power the on-board voltage regulator, but do not connect a USB cable from your computer to the board at the same time. If you do, you will have 2 5V supply outputs connected directly to each other.

    If you will never have external power applied when you have the USB cable hooked up between the Teensy and computer, you do not need to cut the trace. If you intend to not unplug your external 5V power before reprogramming or otherwise utilizing the USB connector, you need to cut the trace, and then yes you will have to always apply the external power.

    You can also supply a regulated 3V3 source to any of the labeled pins, but again you will need to cut the trace unless this power is disconnected before the USB is connected.


    I removed this need on a custom Teensy-based solution I made by using an in-line diode for each of the VUSB and VIN pins. Yes, it wastes some power, but I can either leave my batteries hooked up or not when I connect the USB cable to the computer.

  20. #545
    Thank's MadMatt,

    You're describing just how I thought things worked.
    I wanted to confirm because I'm about send a board design off to OSH Park...
    I didn't want any gotchas...
    The rule of thumb is USB Cable...or External 5V Power...but never both at the same time.

    Thanks again.

  21. #546
    Quote Originally Posted by Burly View Post
    The rule of thumb is USB Cable...or External 5V Power...but never both at the same time.
    Correct, you can leave the trace alone then. And 5V through VUSB, the USB connector itself, or VIN.

  22. #547
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    One comment, something you could fix/update on the Teensy LC web page (https://www.pjrc.com/teensy/teensyLC.html)?

    The table there says three "FTM Type" timers. But 3.8.1.1 of the manual (https://www.pjrc.com/teensy/KL26P121M48SF4RM.pdf) says the "device contains three low power TPM modules". So I guess the web page should say "TPM Type" timers, i.e. the old timers, not the new fancy extra versatile FTMs.

    Similarly Teensyduino 1.35 header files do define FTM0_SYNC and FTM1_SYNC but these FTM things are not actually found in the manual, only TPM related registers and fields are listed. So perhaps also a header file bug...?

  23. #548
    Senior Member PaulStoffregen's Avatar
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    [QUOTE=JanWagner;136039]One comment, something you could fix/update on the Teensy LC web page (https://www.pjrc.com/teensy/teensyLC.html)?

    I've updated the web page to say "TPM / FTM" with a footnote about their difference. Hopefully that helps?

  24. #549
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    Quote Originally Posted by PaulStoffregen View Post
    I've updated the web page to say "TPM / FTM" with a footnote about their difference. Hopefully that helps?
    Thanks! The footnote helps! Table change, hmm, to clearly show which board offers which type of timer, perhaps you could expand the table like this?
    Code:
    Timers           LC  3.2
      TPM Type*      3    0
      FTM Type       0    3
      PWM Outputs   10   12

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