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Thread: Recommend the right Teensy for the project.

  1. #1
    Junior Member
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    Jul 2020
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    Recommend the right Teensy for the project.

    Hi,

    I am really new to the Teensy and I have spend a lot of time searching through this forum for answers but finally decided to register on the forum as post this thread.


    For my project I need to read adc values for 9 inputs at atleast 1000 times per second, so 9000 values every second in total. Each set of these 9 values needs to be sent to a PC over serial USB before reading another set and repeating this process.

    Can Teensy 3.5 handles both the tasks or should I choose external ADC interfaced with teensy 4.0(not a preferred choice)

    Thanks a lot.

  2. #2
    Senior Member+ MichaelMeissner's Avatar
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    I have no idea in terms of the ADC speeds, but if you are sending stuff to the PC, note that before Teensy 4.0, the Teensys used USB 1.0 speeds (12Mbits/s maximum). Teensy 4.0/4.1 moves to USB 2.0 speeds (480Mbits/second), but note often times the problem is getting the host OS to be able to read the stream full throttle (i.e. drinking from a fire hydrant).

    A side issue is some USB hubs will lower the overall speed from the devices to match the slowest device. I.e. if you put a Teensy 4.0 on one of these USB hubs, and you hook up a mouse/keyboard, you might find the speed throttled down.

  3. #3
    Junior Member
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    I have 9 values of adc that can be represented as a string in 44 bytes if I convert everything to a string like 'v1,v2,v3..v9', plus additional 2 bytes for new line characters. So in total 46 bytes every millisecond comes to 46000 bytes i.e 46KBps. If I can handle this on PC side Teensy 3.5 should not have any problem given its 12Mbit USB support. I really need the 13 bit ADC on Teensy 3.5 for better resolution of the adc values as 4.0 only has 10 effective adc resolution.

    I have taken a note of your USB hub comment. I'll make sure that the hub does not become a bottleneck.

    Thank you for your response.

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