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Thread: SD read speed in raw 512 byte mode on Teensy 3.6 and 4.0

  1. #1
    Junior Member
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    Oct 2019
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    SD read speed in raw 512 byte mode on Teensy 3.6 and 4.0

    I have a real-time audio application where I need to overlay audio samples in an output audio stream. The Teensy memory can't hold the samples, so they well be held on an SD card. I need high speed access to the SD so I'm going to use raw 512 byte mode. I need to make calculations for accessing arbitrary 512 byte blocks. It seems like I could make calculations for read speed, but I'm sure there's twelve catches. Can anyone offer data on block SD reads for Teensy 3.6 and 4.0?

  2. #2
    If you are asking for code on block SD read then I recommend the library SimpleSDAudio.
    Yesterday I opened a post "speed up SD card transfer" asking how to speed up SD data transfer with that library. The library initially is written for Arduino controllers with 16 MHz. I modified it for Teensy 3.2. But my problem with this library is that I don't know how to use the much higher clock rates of Teensy controllers to speed up data transfer. If you can solve that problem you have a solution for your app and it helps me too :-)

  3. #3
    Junior Member
    Join Date
    Oct 2019
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    10
    A library probably wont work for me. The audio work I need to do is unorthodox and very specific. All I really need is a function I pass an address to and I get the 512 byte block back when an interrupt is thrown on completion. I need to calculate how many cycles it would take to run.

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