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Thread: Teensy 3.6 diy board

  1. #26
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    vbat pin it's for Backup battery supply for RTC i do not think that should be connected.

  2. #27
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    from K66 reference manual:

    NOTE
    An attempt to access an RTC register, except the access control
    registers, results in a bus error when:
    • VBAT is powered down,
    • the RTC is electrically isolated, or
    • VBAT POR is asserted.
    http://pjrc.com/teensy/K66P144M180SF5RMV2.pdf page 1338

    The Teensy startup code tries to access an RTC register.

  3. #28
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    Quote Originally Posted by HWGuy View Post
    from K66 reference manual:


    http://pjrc.com/teensy/K66P144M180SF5RMV2.pdf page 1338

    The Teensy startup code tries to access an RTC register.
    Νow works perfectly,uploading the sketch "blink" and flashes led.
    Thank you very much HWGuy.

  4. #29
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    Τhe crystals 16Mhz and 32kHz no need capacitors?

  5. #30
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    It depends on the used crystals. With the crystals from reply#22:
    16Mhz: 2x20pF
    32kHz: none

  6. #31
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    Quote Originally Posted by HWGuy View Post
    It depends on the used crystals. With the crystals from reply#22:
    16Mhz: 2x20pF
    32kHz: none
    HWGuy thanks for your answers.
    Why the crystal 32kΗz he doesn't want capacitors?
    By what criteria we choose if we will do or not capacitor?
    For example the crystal wants;
    Last edited by thanos; 12-10-2016 at 09:21 PM.

  7. #32
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    Here Paul recommends 20pF load capacitors for a 18pF crystal (Teensy 3.1): https://forum.pjrc.com/threads/27378...ll=1#post60672

    The 16MHz crystal on the Teensy 3.2, 3.5 and 3.6 has a load capacitance of 9pF.

    For example the crystal wants;
    no additional load capacitors needed

    Paul recommends a 12.5pF crystal for RTC (Teensy 3.0): https://forum.pjrc.com/threads/724-3...ull=1#post1561



    the load capacitors are calculated with this formula

    CX = 2 * CL - CPARA - CINT
    19pF = 2 * 18pF - 7pF - 10pF



    Last edited by HWGuy; 12-11-2016 at 03:47 AM.

  8. #33
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    Quote Originally Posted by HWGuy View Post
    Here Paul recommends 20pF load capacitors for a 18pF crystal (Teensy 3.1): https://forum.pjrc.com/threads/27378...ll=1#post60672

    The 16MHz crystal on the Teensy 3.2, 3.5 and 3.6 has a load capacitance of 9pF.

    no additional load capacitors needed

    Paul recommends a 12.5pF crystal for RTC (Teensy 3.0): https://forum.pjrc.com/threads/724-3...ull=1#post1561



    the load capacitors are calculated with this formula

    CX = 2 * CL - CPARA - CINT
    19pF = 2 * 18pF - 7pF - 10pF



    Why a teensy 3.2,3.5 and 3.6 there are no capacitors in the crystals?

  9. #34
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    Quote Originally Posted by thanos View Post
    Why a teensy 3.2,3.5 and 3.6 there are no capacitors in the crystals?
    Think about it!
    maybe they are not needed. Maybe they are chosen the way, that sufficient capacity exists (internal and external).
    (HWGuy gave you a formula)
    BTW, search the forum for other successful DIY approaches, which also discuss the actual 3.2 designs. It really helps.

  10. #35
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    Quote Originally Posted by thanos View Post
    Why a teensy 3.2,3.5 and 3.6 there are no capacitors in the crystals?
    They're built inside the chip. In fact, there's 4 capacitors inside the chip, 2pF, 4pF, 8pF and 16pF, which can be turned on/off by software control.

  11. #36
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    regarding the circuit in reply #24

    have a look at the "Recommended connection for unused analog and digital
    pins" section in the K66 datasheet. http://pjrc.com/teensy/K66P144M180SF5V2.pdf page 79 & 80

    for example:
    VREFH - Always connect to VDD potential
    VREFL - Always connect to VSS potential

  12. #37
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    Quote Originally Posted by PaulStoffregen View Post
    They're built inside the chip. In fact, there's 4 capacitors inside the chip, 2pF, 4pF, 8pF and 16pF, which can be turned on/off by software control.
    Thanks paul.

    Quote Originally Posted by HWGuy View Post
    regarding the circuit in reply #24

    have a look at the "Recommended connection for unused analog and digital
    pins" section in the K66 datasheet. http://pjrc.com/teensy/K66P144M180SF5V2.pdf page 79 & 80

    for example:
    VREFH - Always connect to VDD potential
    VREFL - Always connect to VSS potential
    HWGuy thanks for clarifying,the schematic in post 24 is not the final.
    Just i did the most simple schematic to see if can the bootloader chip to programming the MK66FX1M0VLQ18.

  13. #38
    if there's going to be custom boards, we'll need the bootloader chips to be compatible with the k66 mcu (the pjrc page says it's only up to teensy 3.2)

  14. #39
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    Quote Originally Posted by pix-os View Post
    if there's going to be custom boards, we'll need the bootloader chips to be compatible with the k66 mcu (the pjrc page says it's only up to teensy 3.2)
    I also want to build a custom board and don't know if i can order the bootloader or not.
    Just forgot to update the website or are the bootloader still not available for the "teensy 3.6" custom boards?
    Thanks

  15. #40
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    Quote Originally Posted by PaulStoffregen View Post
    They're built inside the chip. In fact, there's 4 capacitors inside the chip, 2pF, 4pF, 8pF and 16pF, which can be turned on/off by software control.
    Hello after a long time,the crystals 16Mhz and 32.768kHz what load capacitance it must have everyone??

    Thanks.

  16. #41
    Senior Member PaulStoffregen's Avatar
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    About 8 to 10 pF for 16 MHz and 12 or 12.5 for 32.768 kHz.

    Crystals with higher capacitive load specs can be used, but you'd need to edit the default code or add external caps.

  17. #42
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    Ok paul thanks.

  18. #43
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    Hello,
    i want to use the pins PTA6,PTA7,PTA8 of the microcontroller MK66FX1M0VLQ18.I want to declare these pins as INPUT_PULLUP as in the example below:

    pinMode(21, INPUT_PULLUP); //exmple to 21 pin

    Τhese pins PTA6,PTA7,PTA8 are not registered with some number,these pins correspond to a number or because they are not available on the board teensy 3.6(version MK66FX1M0VMD18) they have not been registered??

    A solution is to state it:

    PORTA_PCR6 = PORT_PCR_MUX(1) | PORT_PCR_PE | PORT_PCR_PS;
    PORTA_PCR7 = PORT_PCR_MUX(1) | PORT_PCR_PE | PORT_PCR_PS;
    PORTA_PCR8 = PORT_PCR_MUX(1) | PORT_PCR_PE | PORT_PCR_PS;

    Correctly?
    Last edited by thanos; 12-20-2017 at 01:18 PM.

  19. #44
    Senior Member+ KurtE's Avatar
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    Looks correct to me...

    Probably more work than benefit, but you could of course also update your setup to have more registered pins. Like maybe create a new Variant in boards.txt...

    Then update the pin Tables...
    Would probably require changes to:
    Code:
    core_pins.h - Add in the info about the new pins (pin, mask, port register, ...), and counts - not hard but tedious. 
    pins_arduino.h - If you want some of them to work as Analog pins
    pins_tensy.c - to add to bitband.

  20. #45
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    I will try it kurte thanks.
    One last question,on the pins i mentioned above i will put push buttons.
    I am thinking of turning on the internal pullup resistors on these pins and do not put external pullup resistors,i will not have a problem properly?

  21. #46
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    If you don’t find the answer in the reference manual, you can still try to activate the GPIO MUX for these pins, configure their port control registers for the internal pull-up, let the code run doing strictly nothing and check the differential inner resistance with a resistor towards ground and a multimeter. Learning by doing is the preferred way to go!

  22. #47
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    Generally when we want to use push buttons it is good to use internal pullup resistors or to mount external pullup resistors??
    I'm asking why in my project i have activated the internal pullup resistors.Like here.

  23. #48
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    I have had reasonable luck using the internal weak pull up resistors for things like buttons. You simple need it to be strong enough to register as a high if using PU or LOW if PD...

  24. #49
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    Hello,
    i want to use in my project the function hibernate to have very little consumption.
    I found this voltage regulator which has very low quiescent current but it's very low output current 85mA.
    In my project i use two channels spi,three channels uart,three analog port,one channel i2c,sd card,one dac port and 24 io port,all peripherals and sd card powered from another voltage regulator.
    The 85mA output current which gives is enough or i will need more??I use the teensy 3.6.

  25. #50
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    Quote Originally Posted by thanos View Post
    Hello,
    i want to use in my project the function hibernate to have very little consumption.
    I found this voltage regulator which has very low quiescent current but it's very low output current 85mA.
    In my project i use two channels spi,three channels uart,three analog port,one channel i2c,sd card,one dac port and 24 io port,all peripherals and sd card powered from another voltage regulator.
    The 85mA output current which gives is enough or i will need more??I use the teensy 3.6.
    May not be sufficient. over 100 mA @ 5V is frequent observed when writing to uSD.

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