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Thread: Audio IN without audio board

  1. #1
    Senior Member
    Join Date
    Nov 2015

    Audio IN without audio board

    Is it possible to add one audio input without the audioboard?
    the problem is that in our project we are running out of pins and audioboard require many pins with i2s connection.

    Is it possible to add a ADC?
    Is difficult to use with the audio library?

    we use teensy 3.6

    Last edited by urbanspaceman; 09-06-2019 at 01:39 PM.

  2. #2
    Senior Member Blackaddr's Avatar
    Join Date
    Mar 2017
    Many of the Teensy's have a built in ADC, though it's only 12-bit. Many people use it for audio when they don't need high quality. Are you using a Teensy 3.5/3.6 and running out of pins? If not, consider one of those. If you already are, and need more I/O you may have other options depending on how fast the I/O must be. If it's for low speed signals, or controls likes buttons, LEDs, etc. You could add a second Teensy (like an LC) to handle all the low speed I/O, and have it communicate with the main Teensy via a UART or SPI connection.

  3. #3
    Senior Member
    Join Date
    Nov 2015
    Ciao Blackaddr
    I think one of the onboard ADCs is more than enough. I have to check if we can use one of those pins or change the circuit a bit to use them


  4. #4
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Ayer Massachussetts
    As Blackaddr says, there are various ways to do analog input.

    However, if your inputs are digital you can use the I2S pins. Unfortunately, the Teensy 3.x pinouts did not list the I2S pins. Note, they overlap with the SPI pins, which is why the audio board uses alternative SPI pinouts. According to my notes, on the 3.6, the I2S pins are:
    • Pin 9: BCLK
    • Pin 11: MCLK
    • Pin 13: RXD0
    • Pin 15: TXD1
    • Pin 22: TXD0
    • Pin 23: LRCLK
    • Pin 38: RXD1

    There are some alternates for I2S in the 3.5/3.6 boards as well.

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