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Thread: deport TFT from Teensy

  1. #1
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    deport TFT from Teensy

    Hello,

    My plan is to deport the TFT display to make the screen universal for various applications.

    Click image for larger version. 

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    The connection between the Teensy and the screen could be by radio or by wire link.

    On the Teensy side, the information to be sent to the screen could be data from a spectrum analyzer.

    So I wonder what would be the best way to transmit the data to the TFT module (itself driven by an arduino, esp, ..).

    Ideally, a wireless link would be more practical (bluetooth, RF433, Infra Red, ..) unless speed constraints force me to use a wired link (i2c, serial)

    So I would like to have your opinion on the method to use, with or without wire.
    Thanks you
    Fred
    Last edited by fred_france; 01-12-2021 at 06:09 AM.

  2. #2
    Senior Member+ Frank B's Avatar
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    The default speed is 30 MBIT.
    You'll need an interface and a CPU which can handle that, or live with way slower speeds.

  3. #3
    Senior Member+ Frank B's Avatar
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    Best is to use a Teensy on the display, if you want it fast.

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    Quote Originally Posted by Frank B View Post
    The default speed is 30 MBIT.
    what is the speed of what part?

  5. #5
    Senior Member+ Frank B's Avatar
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    Spi to the display is 30MBit on Teensy.

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    Quote Originally Posted by Frank B View Post
    Spi to the display is 30MBit on Teensy.
    ok I understand, maybe that's why I can't find a screen of this size with an I2C bus

    I'm afraid of having to directly link the TFT to the teensy
    unless I'm wrong but no protocol will be as fast as SPI (serial, i2c, RF link ..)

  7. #7
    Senior Member+ Frank B's Avatar
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    As said, you can just use a Teensy on the display.
    It can handle the graphics , and you can send just the values for your spectrum display over *whatever* interface. That would be low traffic. I'd recommend serial.

  8. #8
    Senior Member+ Frank B's Avatar
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    I understand, you want to save money with a cheap cpu on the display, but that is the wrong place..

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    Quote Originally Posted by Frank B View Post
    I understand, you want to save money with a cheap cpu on the display, but that is the wrong place..
    it is not an economic problem (the TFT costs 5 dollars in china), but rather ergonomic.
    If I want to take measurements on the Teensy, it is convenient for me to have the result several meters away

  10. #10
    Senior Member+ Frank B's Avatar
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    With my proposed solution you can use a slow connection.
    Bluetooth maybe?

  11. #11
    Senior Member fdaniels's Avatar
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    Maybe its easier to have the Sensors away from the Teensy+Display?

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    Quote Originally Posted by fdaniels View Post
    Maybe its easier to have the Sensors away from the Teensy+Display?
    the sensor is the microphone, if it is possible to deport it and send the audio stream by air? (without going through a wireless microphone system but with a module that integrates well with the Teensy, but I don't know which one

  13. #13
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    Quote Originally Posted by Frank B View Post
    With my proposed solution you can use a slow connection.
    Bluetooth maybe?
    for the test results yes it should work, but for the FFT (spectrum analyzer), I don't know if it is possible to send on the air the 512 bins values ​​very quickly to display them on the TFT?

  14. #14
    Senior Member+ Frank B's Avatar
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    512 bytes shouldn't be a big problem.
    But how do you display 512 bins on the 320x240 display?
    I bet you can transfer much less than that.

    Maybe 16 bins are enough?

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    Quote Originally Posted by Frank B View Post
    512 bytes shouldn't be a big problem.
    But how do you display 512 bins on the 320x240 display?
    ?
    you're right, the screen is to small, max 320 bins in landscape format (1 bin= 1 pixel)

  16. #16
    Senior Member+ Frank B's Avatar
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    In addition all these bins don't give you more usable Information than, lets say 32 or less..
    If you just look at it, with the eyes.

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    OK, I haven't tried it yet (I'm getting the TFT this weekend).
    thank you for your advice

    so if I summarize, it is not possible to replace the SPI BUS with a radio solution, but for a small volume of data (example: 320 data each [I do not know the calculation speed of FFT1024] milli-seconds) , it is possible

  18. #18
    Senior Member+ Frank B's Avatar
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    The "bins"-display is more important.
    You don't need more than 20Hz (or even less, depends on how you're doing it ) for a good display. Cinema is 25Hz.
    But you can smooth your data. It looks even better to use less, because it will less flicker.

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    Senior Member+ Frank B's Avatar
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  20. #20
    Senior Member+ Frank B's Avatar
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    The last one is a little too slow, maybe, but you got the idea

    Als this was done on a "slow" Teensy 3.2

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    awesome !

    is this ESP on the last video?
    is the audio stream coming from wifi?

  22. #22
    Senior Member+ Frank B's Avatar
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    Yes, it was a mp3 radio stream form a local station, esp8266 for wifi. Teensy 3.2 does mp3 decoding sound and display.

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    great project, I like it, it gives me new DIY ideas

    can the code be visible?

  24. #24
    Senior Member+ Frank B's Avatar
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    I lost it some years ago. BTW, the SPI was 60MHz, so I had to run the Teensy 3.2 with 120MHz. But the CPU usage is low. It's the % value in the headline.
    The mp3-library is on my github.

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    Where can I find your project on github ?

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