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Thread: Need infos on I2S and DMA of Teensy 4

  1. #1
    Junior Member
    Join Date
    Sep 2021
    Posts
    1

    Need infos on I2S and DMA of Teensy 4

    Hello, I have several Teensy 4.1 for almost a year. I'm looking to make an SDR receiver out of them.

    I have currently managed to draw a waterfall and a spectrum analyzer on a TFT screen. I can receive the HF bands.

    Nevertheless, I use the internal ADC of the Teensy!
    I know (since the beginning) that it is incorrect, the dynamic range is not great for receiving I/Q signals!

    My problem was to get the algorithms and the RF front end right. It's done, it works.
    Currently I have to fix this defect, I would like to use a 24 bit audio ADC. I ordered a CS5343. I do not want to use the Teensy audio shield.

    The CS5343 uses an I2S bus. I absolutely must employ the DMA to receive my samples.

    I've been browsing the net for a few hours looking for information about Teensy, I2S and DMA. I must not be searching very well: I can only find fragmented information.

    Could someone point me to a starting point? I don't even know if I should wire my CS5343 ADC as an I2S "master" or "slave".

    I'm not asking you to do the work for me, and I think someone has already asked a question similar to mine. I'm sorry about that.

    I would just like some direction. I have looked at the Teensy audio library sources. I understood (probably wrongly) that it only supports one mode of the I2S ("master" or "slave", I don't know).

    I would rather avoid using the Teensy audio library. I only need I2S and DMA. The Teensy is powerful, but the resources are still limited! Maybe I'm wrong! I would like to have an opinion.

    Thanks for your help.

  2. #2
    Member
    Join Date
    Sep 2021
    Posts
    70
    Yes, you're wrong. The Audio lib adds almost no overhead. An alternative is not worth hours of tinkering. And it supports both, master and slave.

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