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Thread: General questions about Teensy 3.2

  1. #1
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    General questions about Teensy 3.2

    In the Teensy 3.2 schematic there are a few random wires that don't connect to anything. On the nets which connect the USB connector pins 2, 3, and 4 to name a few. What are those supposed to be?
    The pinout images show TX1, RX1, and other functions duplicated on multiple pins but grayed-out. Can you reconfigure Serial1 to use either pins 0 & 1 or 5 & 21?
    What is the purpose of the secondary smaller microcontroller on the Teensy? At first I thought it might be acting as a USB-UART converter (like an FTDI) but it isn't connected to the USB.
    The silk screen around the surface pads for pins 29-33 and 28-24 implies that there might be a 0.1" pitch header that can be soldered on so that those pins could be brought down to a mother board socket. Is there a recommended part to use for that?

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    Senior Member+ MichaelMeissner's Avatar
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    Yes, you can use the alternate Serial, I2c, and SPI pins. https://forum.pjrc.com/threads/32261...8102#post98102

    The second processor is the boot processor. It is responsible for installing new software in the Teensy.

    There are several designs to get access to the bottom pins:


    Here is a posting collecting many of the tips: https://forum.pjrc.com/threads/25395...ips-and-Tricks

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by tonyf View Post
    In the Teensy 3.2 schematic there are a few random wires that don't connect to anything. On the nets which connect the USB connector pins 2, 3, and 4 to name a few. What are those supposed to be?
    Those represent the test points. They're tiny pads on the bottom side used to access certain signals when we test each Teensy on a bed-of-nails test fixture.

    Here's an old writeup about the testing process, which photos.

    https://www.kickstarter.com/projects...a/posts/305527

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    How does the second MCU obtain the new software to install on the main MCU? I don't see any connections for the secondary MCU to get new software other than through the main MCU. Can the secondary MCU access the main MCU's USB through JTAG or something?

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    Quote Originally Posted by tonyf View Post
    Can the secondary MCU access the main MCU's USB through JTAG or something?
    This is part of the beauty of teensy,
    As far as I understand:
    when main MCU (K20) is running and USB is activated, user (Teensyduino, PC application etc) can put teensy into programming mode (equivalent to prog button press)
    when main MCU is NOT running, say crashed or USB not active, the pressing prog button puts teensy into programming mode
    when in programming mode, second mcu copies bootloader program into RAM of main MCU and restarts SW. Bootloader is then waiting for PC to download hex file which is then copied to flash, as usual.
    Protocol is proprietary to PJRC but similar to SWD programming (I think)
    Overall, consider the second MCU as a smart bootloader ROM

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    Hello i want to ask you what is the maximum frequency that has been tested that it works without any problem the teensy3.2;
    Asks why i want to put into my project that will operate 24 hours every day.

    Thanks.

  7. #7
    Senior Member Ben's Avatar
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    You can reliably overclock the Teensy to 96MHz, this is officially supported inside the Arduino/Teensyduino IDE.

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    Οver from the 96 MHz works unstable??
    In 120MHz there's problem?

    Thanks.

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    Quote Originally Posted by thanos View Post
    Οver from the 96 MHz works unstable??
    In 120MHz there's problem?

    Thanks.
    On T3.2 I only use 144 Mhz, without problems so far. But as ben said over 96 MHz, it is own risk territory

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    Ok guys,the libraries spi,wire and the function micross() in 144miz operate properly ??

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    Quote Originally Posted by thanos View Post
    Ok guys,the libraries spi,wire and the function micross() in 144miz operate properly ??
    if you use standard Teensy code (e.g. the one provided by teensyduino) only set F_CPU to 144000000 in makefile option or use Arduino IDE
    you may have to edit yourArduinoInstallation\arduino-1.6.9\hardware\teensy\avr\boards.txt and uncomment the lines

    Code:
    #teensy31.menu.speed.168opt=168 MHz optimized (overclock)
    #teensy31.menu.speed.144opt=144 MHz optimized (overclock)
    #teensy31.menu.speed.120opt=120 MHz optimized (overclock)
    to see the speeds in Arduino IDE

    Caveat: I never got 168 MHz proper working on my T3.1(2). However, I did not investigate.

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    Thank you wmxz,the libraries spi,wire and the function micross() in 144Mhz will operate properly??

  13. #13
    Senior Member+ Frank B's Avatar
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    Quote Originally Posted by thanos View Post
    Thank you wmxz,the libraries spi,wire and the function micross() in 144Mhz will operate properly??

    yes, they work.

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    Νice,go to experiment.

  15. #15
    Senior Member PaulStoffregen's Avatar
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    Since these messages, the Teensy 3.6 launched on Kickstarter. If you're looking for faster clock speeds, Teensy 3.6 is the board to use!

    https://www.kickstarter.com/projects...ensy-35-and-36

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    Thanks paul,since properly operates at 144 MHz think that I will be okay.

  17. #17
    Senior Member PaulStoffregen's Avatar
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    At least a few people have reported occasional problems with 144 MHz on Teensy 3.2. I'd be reluctant to depend on that speed.

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