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Thread: Teensy 4.0 filters without audio shield

  1. #1

    Teensy 4.0 filters without audio shield

    I want to use the Teensy 4.0 board for some communications-quality audio filters (LPF, HPF, BPF, etc). It seems to me that the on-board ADC and DAC should be sufficient for this. Can someone point me to a project where someone has done this?


  2. #2
    Senior Member DD4WH's Avatar
    Join Date
    Oct 2015
    Central Europe
    Hi Joe,

    with the standard audio lib you could use

    * biquad filters
    * FIR filters

    with a bit more fiddling you could use the audio lib queue object to obtain your audio blocks and do convolution filtering to give you the desired response.

    The audio lib standard objects can be found in the Teensy audio lib GUI, the convolution filtering code examples can be found in the forum search function

    Please note that the T4 does NOT have an DAC, it is not built into the chip. But for a bit lower quality audio you can use the MQS-output (do a forum search on that)
    The T4 ADC has an effective number of bits of about 10 to 11.

  3. #3
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Audio-Library code for the Teensy 4 ADCs is to be done.

    I'd just use an Audio Shield at the moment.

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