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Thread: Teensy 3.5 & 3.6 Schematic Posted

  1. #51
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    thanks for clarification, i did not find this mentioned anywhere, except deep in 'kinetis.h'
    however i'm still puzzled because

    pinMode(13,OUTPUT);

    works, while

    GPIOC_PDDR = B00100000;

    does not work...

  2. #52
    Senior Member PaulStoffregen's Avatar
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    Looks like you're applying your experience with the simple AVR chips to these newer, more complex ARM chips.

    Maybe you're not aware of the PORT registers which control a mux that connects the pin to 1 of 8 possible functions? The GPIO registers are one of those 8 functions. If you don't configure the mux to connect the pin to GPIO, then manipulating the GPIO registers has no effect.

    All of this stuff is documented in Freescale's reference manual. It's all done in the Teensyduino core library which implements pinMode and digitalWrite.

  3. #53
    Senior Member PaulStoffregen's Avatar
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    All the documentation can be found here:

    https://www.pjrc.com/teensy/datasheets.html

    If you're only accessing the peripherals, you only need the reference manual for the chip you're using.

    However, if you're going to use interrupts natively, I highly recommend you get Joseph Yiu's book. There are important differences between AVR's simplistic and very limited interrupt system and Cortex-M's far more advanced priority nested interrupt controller. Many AVR experts have gone down this path, especially applying their knowledge of AVR's GIE (global interrupt enable) status bit, wrongly assuming it's the same as the NVIC's PRIMASK feature. If you're going to do low-level register programming and get into the CPU's features, you really need that book. The ARM core isn't documented much in Freescale's reference manual (nor the datasheets from any of the other manufacturers). That book is the essential info about the processor.
    Last edited by PaulStoffregen; 04-22-2017 at 02:24 PM.

  4. #54
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    thanks for your answer.
    apart from reading the ref manual i just found that after pinMode being called once
    - which - i guess - inits the muxer it is possible to change direction by using PDDR directly.

    i am planning to make a 16bit address/databus adapter for an old large machine and was looking for fast parallel i/o

  5. #55
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by 42loop View Post
    planning to make a 16bit address/databus adapter for an old large machine and was looking for fast parallel i/o
    With this added bit of info, I'd recommend looking at the UTFT library. It has native parallel GPIO to displays. Maybe some usable code there?

  6. #56
    Senior Member+ Frank B's Avatar
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    what speed is needed ? i guess a very simple approach is more than ok.
    usually, the speed of a tensy is underestimated...

  7. #57
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    I had missed a couple of components in the schematics, sorry about that...

    Anyways, thanks to all of you guys I finished the Eagle schematics. Hopefully it'll be a boost start for others in their quest for custom Teensy.

    I changed the fuse to the one which HWGuy suggested: Bourns MF-FSMF050X.

    As advised here, I picked ECS-160-8-30B-CKM for the 16 MHz oscillator. For others who come across, consult here and here for careful layout design of your oscillator.

    Finally, for the 32.768 kHz crystal I picked ECS-.327-CDX-1128.

    If you find any faults, please let me know so I'll update this post.

    Update (May 6th, 2017): Fixed some disconnected joints on the right side of micro controller. Also, TPDS014 and LP38691 are replaced with their fixed versions.
    Attached Files Attached Files
    Last edited by kiserth; 05-06-2017 at 03:20 PM.

  8. #58
    Senior Member+ Frank B's Avatar
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    Would you mind sharing your eagle-project as a starting point for other users ?

  9. #59
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    Sure, I fixed the post.
    Last edited by kiserth; 04-23-2017 at 03:36 PM.

  10. #60
    Senior Member+ Frank B's Avatar
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    great, thank you.

  11. #61
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    Hello again everyone,

    As my project progressed, it seemed proper to switch for Altium. So I redrew the schematics.

    Here are the libraries I made:
    • MK66LFX1M0VMD18
    • MKL02Z32VFG4
    • TPD3S014
    • LP38691
    • PMEG4010CPA (double diode)
    • DM3D-SF (microSD slot)
    • MF-FSMF050X-2 (fuse)
    • Crystal and oscillator


    ICs were easy to make as Altium had a wizard for this purpose. 3D model for the microSD slot was downloaded from this GitHub repository, and other components (resistors, capacitors, ferrites, pads and micro USB port) were from here.

    Hope you enjoy, and let me know if you find any flaws

    Update (May 30th, 2017): Fixed the missing A4 pin on the micro controller.
    Click image for larger version. 

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    Last edited by kiserth; 05-30-2017 at 09:04 PM.

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