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Thread: Need infos on I2S and DMA of Teensy 4

  1. #1
    Junior Member
    Join Date
    Sep 2021

    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
    Join Date
    Sep 2021
    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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