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Thread: Using two Teensy LC to handle 16 rotary encoders

  1. #1
    Junior Member
    Join Date
    Mar 2018
    Posts
    5

    Using two Teensy LC to handle 16 rotary encoders

    Hello,
    For a midi controller i'm trying to add 16 rotary encoders (with push button and led: https://www.sparkfun.com/products/10596) to my Teensy 3.2
    I also wan't to add a lot of other stuff like displays and extra buttons and leds. A google research suggested that multiplexing rotary encoders with a normal analog/digital multiplexer is a bad idea. I found mortenkopfs example using the MCP23S17 but setting this up seems quite complicated.
    When I connected my first encoders to the teensy using the teensyduino encoder library I was suprised how easy it was and how good the results where (even when just connecting the pins directly to the teensy without any debounce circuit).
    So it would be ideal to just use teensys instead of fiddeling around with chips like the MCP23S17.
    Before I buy all my parts I just wanted to ask if it would be a good setup to use two teensy LC to handle the encoders and my teensy 3.2 as my main teensy having the actual programm and handeling MIDI and the extra buttons and leds. The two LC teensys would be connected via the serial ports to the main teensy.
    Because each encoder has two LEDS and a button i'd still run out of pins. Would it be possible to multiplex the leds and/or buttons and only connect the encoders A and B pins directly?

    thanks
    Arno

  2. #2
    Senior Member
    Join Date
    Apr 2013
    Posts
    1,938
    There are a number of ways to get more IO

    https://www.evilmadscientist.com/201...ulbdial-clock/
    https://www.pjrc.com/teensy/td_libs_Keypad.html\
    https://www.adafruit.com/product/593
    And many others, all have trade offs as you scale up

    If this is a one off project I'd be tempted just to go to some sensible number encoders per LC and just have everything duplicated three or four times to be easy to work with. Depends on how much time in design you want to trade for time in $.

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