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Thread: Teensy 4.0 MicroSD Socket

  1. #1
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    Teensy 4.0 MicroSD Socket

    Hi Paul,

    I noticed on the Teensy 4.0 pinout sheet, that the microSD pins are given as smt pads on the bottom side of the board.
    Is there a specific microSD socket that we should order?

    More generally, is there an imminent plan to release a 4 series board with the form factor of Teensy 3.5-3.6 (i.e. microSD on board + more pins accessible)? The 4.0's extra computational oomph would be nicely paired with a way to store and access large data sets.

    Thanks!

    -Josh

  2. #2
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    Question about the product page... It looks like there are two copies of the top side illustration, none of the bottom.

    Congratulations on the new release! Two units ordered, looking forward to their arrival.

  3. #3
    Senior Member+ KurtE's Avatar
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    There is a set of 8 pads that are spaced at .1mm, that is setup to allow you to solder on a ribbon connector like: https://www.digikey.com/products/en?...=609-1788-1-ND
    You need to solder one of these on the bottom of the T4 and one on your breakout board. Then I am using a ribbon connector to connect them:
    Which I believe I am using: https://www.digikey.com/products/en?keywords=AE11351-ND

    You are then free to use whatever SD connector you wish. Again the one I purchased was: https://www.digikey.com/products/en?...ds=HR1941CT-ND

    But again someone else may have better suggestions.

    As for back of card. The image on the beta thread: https://forum.pjrc.com/threads/54711...irst-Beta-Test

    shows both sides of the card, although it does not show the actual Teensy...

  4. #4
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by KurtE View Post
    As for back of card. The image on the beta thread: https://forum.pjrc.com/threads/54711...irst-Beta-Test

    shows both sides of the card, although it does not show the actual Teensy...
    Note, the 4.0 product link now has both sides of the card including the back of the Teensy showing the pad locations:


    I imagine Paul is rather busy with all of the things with the release, but it would be nice to replace the pictures with the actual pinout card images now.

    <edit>
    The images are now updated with the real pinout cards.
    Last edited by MichaelMeissner; 08-08-2019 at 10:25 PM.

  5. #5
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    Quote Originally Posted by KurtE View Post
    There is a set of 8 pads that are spaced at .1mm, that is setup to allow you to solder on a ribbon connector like: https://www.digikey.com/products/en?...=609-1788-1-ND
    You need to solder one of these on the bottom of the T4 and one on your breakout board. Then I am using a ribbon connector to connect them:
    Which I believe I am using: https://www.digikey.com/products/en?keywords=AE11351-ND

    You are then free to use whatever SD connector you wish. Again the one I purchased was: https://www.digikey.com/products/en?...ds=HR1941CT-ND

    But again someone else may have better suggestions.

    As for back of card. The image on the beta thread: https://forum.pjrc.com/threads/54711...irst-Beta-Test

    shows both sides of the card, although it does not show the actual Teensy...
    Have you actually installed one of the card connectors on final layout PCB?

  6. #6
    Senior Member+ KurtE's Avatar
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    Yes - Although the first one I tried, I never did get all of the signals to properly work. I have had luck with a second one.

    Some hints that Paul gave me might help:

    Me: it is sort of a pain to solder that ribbon cable on bottom, especially with the white wire… Do you have suggestions on best way?

    Paul: For all the betas, I used Kester 331 lead-based solder with 2331 liquid flux. All hand soldering under a microscope. Cleaned the flux by washing in hot water, then bake dry for 20 min at 170F. Not saying that's necessarily the best way. It is labor intensive, but it also worked pretty well on a few dozen beta boards.

  7. #7
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    There may be some confusion about mounting a microSD card holder directly on the Teensy 4 board as in the 3.5 and 3.6. The board pad pitch is 1.0 mm. MicroSD cards and their connectors are 1.1 mm pitch. So without some kind of adapter as discussed above or an unknown microSD card holder, it's not practical.

  8. #8
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by bicycleguy View Post
    There may be some confusion about mounting a microSD card holder directly on the Teensy 4 board as in the 3.5 and 3.6. The board pad pitch is 1.0 mm. MicroSD cards and their connectors are 1.1 mm pitch. So without some kind of adapter as discussed above or an unknown microSD card holder, it's not practical.
    Indeed to support pins for USB Host and present those SD pins on the tiny bit of space present that wouldn't allow a usable socket to mount without removing USB Host the revision presented was made to allow the pins to be picked up with a cable based connector to take the pins elsewhere to be used.

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