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Thread: Teensy 4.1 number of SPI ports

  1. #1
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    Teensy 4.1 number of SPI ports

    In the teensy comparison chart located at https://www.pjrc.com/teensy/techspecs.html
    it shows that the Teensy 4.1 has 2 SPI ports, but on its page https://www.pjrc.com/store/teensy41.html it states that there are 3 SPI ports.
    Is this a typo in the comparison chart or is it listed as 2 there for a reason?

    I am planning on migrating from 3.6 to 4.1 and our current design uses all three SPI ports so clarification would be much appreciated.

  2. #2
    Senior Member+ KurtE's Avatar
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    There are 3 on both t4 and t4.1. But 3rd on sd pins and on T41 on bottom memory chip pins

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    Quote Originally Posted by KurtE View Post
    There are 3 on both t4 and t4.1. But 3rd on sd pins and on T41 on bottom memory chip pins
    Would I be able to solder on a surface mount 0.05" header to connect an SPI peripheral or is it reserved somehow for QSPI memory chips?

  4. #4
    Senior Member+ KurtE's Avatar
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    Yes you can connect to those pins, not sure about any specific header for it. But if you find one that works...

    I experimented using a few breakout boards and did a quick and dirty castellated extension board to play with those pins.
    Click image for larger version. 

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    A few caveats, you can use these pins for QSPI or other stuff, but not both. That is you have a PSRAM in one, then it uses up all of the pins (except one which is the Chip select for the other slot).

    And the startup code will ping the QSPI to see if there is a PSRAM, which never interfered with what I tested.

    And the QSPI pins and subsystem for spi are different than the SPI2 pins (Low Power SPI)....

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