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Thread: Unable to use PSRAM on Teensy 4.1

  1. #1
    Junior Member
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    Unable to use PSRAM on Teensy 4.1

    Using the test program from https://github.com/PaulStoffregen/te...am_memtest.ino

    Running the program on a bare T4.1 (no other connections, and it's new out of the box), I just see

    EXTMEM Memory Test, 0 Mbyte

    The RAM chip I have is an ISSI
    IS62WVS5128FBLL-20NLI-TR (https://www.mouser.be/ProductDetail/...WS5128FBLL2NIT)

    Any ideas? I am confident about the soldering, and I've repeated the test with a 2nd memory chip. Maybe the chip is not compatible? In that case, which chips *are* compatible (especially in the 8mb size)? At least here in Europe, I haven't had any luck finding the ones mentioned on the official page https://www.pjrc.com/store/psram.html

    Click image for larger version. 

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    thanks!
    Last edited by Jamewi; 09-30-2020 at 01:49 PM. Reason: adding images

  2. #2
    Senior Member+ mjs513's Avatar
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    Not 100% sure that chip will be compatible. A red flag for me from the data sheet shows the maximum clock on that chip is only 20 Mhz. You might want to check this post out: https://forum.pjrc.com/threads/61399...l=1#post243765.

    You might check this link out: https://github.com/TeensyUser/doc/wi...and-psram-pads. It shows a vendor in Germany as well as other vendors.

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by Jamewi View Post
    At least here in Europe, I haven't had any luck finding the ones mentioned on the official page
    EXP Tech in Germany has the correct chip in stock.

    https://www.exp-tech.de/en/platforms...for-teensy-4.1

    And FWIW, your soldering looks excellent. But that ISSI chip just won't work.

  4. #4
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    Excellent, I think it's case closed here. Thanks for pointing to the Wiki and Exp-tech; order on the way already!

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