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Thread: TFT to display ongoing vacuum changes

  1. #1
    Junior Member
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    Jan 2020
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    Greenport NY
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    TFT to display ongoing vacuum changes

    Oh mighty forum, your guidance to my needs is hereby respectfully solicited. - Steve

    Goal: Touch TFT on Teensy 4.0 to display active changes of vacuum pressure
    Assumptions / needs:
    // 0) use Teensy 4.0 in final deployment (currently working with Teensy 3.2)
    // 1) take pressure readings at 1/second with SparkFunMPL3115A2
    // 2) display #1 pressure as a vacuum readings with negative float number in Pascals (Pa)
    // 3) display #2 provide a pulsing progress bar as the pressure changes 10 times/minute.
    // 3a) Example subject to change: (2 sec vacuum motor on + 4 sec no motor) * 10 cycles = 1 minute
    // 3b) Touch TFT display+sensor is remote from the vacuum motor micro-controller
    // 4) display #3 average a baseline negative number (the closest to 0) that were read with a 1 minute sampling
    // 5) display #4 average greatest vacuum achieved within the same 1 minute sampling as 4)
    // 6) put screen asleep after 20 seconds
    // 7) wake up screen by simple touch anywhere
    // 8) battery power recommendation to keep the display working with intermittent user touches (~15/day) for minimum of 15 days
    // 9) need low power warning to support 8) to notify user to change the batteries
    // On my own I'll discover how to rotate screen for horizontal display

    Complete working code in the attached file.

    Thank you.
    Attached Files Attached Files

  2. #2
    Senior Member
    Join Date
    Jul 2020
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    964
    If battery life is an issue there are better options than the Teensy 4. Probably uses more power than a TFT backlight for instance.
    From what I remember there aren't working low power settings yet for the T4, though that may come with time.

    Your application doesn't need any processing power to speak of - are you needing signficant memory storage?

  3. #3
    Junior Member
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    Jan 2020
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    Greenport NY
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    The Teensy 4 does seem a little strong. The processing feels light and there does not seem the need for significant memory storage. I'm still learning how to take advantage of the Teensy microprocessor family. At of this writing I only know the 3.2 and 4. I am open to other suggestions. Thank you for your interest.

  4. #4
    Junior Member
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    Aug 2020
    Location
    Beijing, China
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    Hi Steve, I think the STONE 3.5" HMI meets your requirements.
    This display is controlled by its own instruction sets, you can program a Teensy or Arduino to display any variables like pressure.
    Communication is via RS-232/TTL, powered by DC5V, consumption about 0.8W.

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