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Thread: ILI9341 Questions and misc.

  1. #1
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    ILI9341 Questions and misc.

    Old fart + total newb to Teensy here, so please be patient.
    I bought a 3.2 and an ILI9341 a couple years ago - had numerous projects in mind, but then some "life happens" events got in the way and it all sat in a drawer. I am resurrecting it and going to take another swing at it now. As I get into it, some questions arise.
    1. Using a breadboard setup is handy for a lot of things, but is not very stable when there are a lot of connections, like to the display + other IO. I see there is a PJRC designed breakout board for the 3.2 and the ILI9341 on OSHPark (TG395175), however, if I see it correctly, it is "dedicated" to the display only and there is no apparent way to also conveniently use the other IO of the Teensy at the same time. Am I missing something? Is there a different / better solution available? I have ordered a 3.2 breakout board from TallDog / Tindie - maybe that's the answer.
    2. For much of what I am doing, using screw terminals would be preferable for mos connections. Is there a source for screw terminals that match the spacing of the holes on the breakout board? I have not been able to find any yet.
    3. Given the apparent popularity of this display / touch screen, it seems that someone would have developed and published a set of common UI widgets for it, but I have not been able to find any. Is there a resource I have just not located? It's not a huge issue for me, as I am using the "opportunity" to develop my OOP skills and knowledge and already have a good start on a nice set of widgets (pushbuttons, slider, bar graphs, data display, etc).
    4. With regard to item 3 programming, I have a really stupid question. Does code developed and put in a library format perform any more efficiently than the compiled code in the Arduino IDE? Is there any benefit to creating libraries other than for redistribution purposes and segmenting code for reuse? Is there a preferred (free) C compiler for developing libraries?
    5. Is there a compiled list of various resources for Teensy related hardware somewhere? Sourcing stuff can be very time consuming when you aren't always sure what you are even looking for.
    Apologies if I am looking for quick and easy answers as opposed to doing extensive research. Like I said, I'm old - there are only so many days left. I'm just trying to keep the brain cells going as long as I can with this type of activity.
    Warning: More questions to come on a variety of topics. There's a lot to learn. Is this the right place?

  2. #2
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    I can answer your second question. There are many sources, just search for "screw terminal 2.54mm".
    This is one of them:
    https://www.pololu.com/category/177/...erminal-blocks

  3. #3
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    neurofun - awesome, just what I'm looking for - thanks!!

  4. #4
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by EddieLeo View Post
    Old fart + total newb to Teensy here, so please be patient.
    I bought a 3.2 and an ILI9341 a couple years ago - had numerous projects in mind, but then some "life happens" events got in the way and it all sat in a drawer. I am resurrecting it and going to take another swing at it now. As I get into it, some questions arise.
    1. Using a breadboard setup is handy for a lot of things, but is not very stable when there are a lot of connections, like to the display + other IO. I see there is a PJRC designed breakout board for the 3.2 and the ILI9341 on OSHPark (TG395175), however, if I see it correctly, it is "dedicated" to the display only and there is no apparent way to also conveniently use the other IO of the Teensy at the same time. Am I missing something? Is there a different / better solution available? I have ordered a 3.2 breakout board from TallDog / Tindie - maybe that's the answer.
    I tend to use prototype boards and solder in connections for various things. For example my current board has:
    • 2 sets of female headers with 24 columns for mounting Teensy 3.x, LC, or Teensy 4.0;
    • An extra row of headers, so I can add jumpers on the fly like you do on a breadboard;
    • An area for SPI displays that has the basic SPI pins broken out (SCLK, MOSI, Vin, Ground, 4 CS/DC/reset pins, and MISO). I make wires for each monitor to map my standard configuration to the wire the particular display has, and allowing 2 displays for doing uncanny eyes (with pull-up resistors for the CS pins);
    • An area for hooking up I2C devices (complete with the necessary pull-up resistors);
    • Connections for Serial1;
    • 3.3v -> 5v converters for WS2812B leds (or neopixel as Adafruit calls them);
    • In the past I often did a separate 3.3v -> 5v conversion for I2C, but I don't think I have any 5v i2c devices I use any more.


    Unfortunately, I touched the soldering iron to some of the female headers, so I'm in the middle of rebuilding it (and of course redesigning it).

    FWIW, here is my current favorite prototype board for soldering:


    Quote Originally Posted by EddieLeo View Post
    2. For much of what I am doing, using screw terminals would be preferable for mos connections. Is there a source for screw terminals that match the spacing of the holes on the breakout board? I have not been able to find any yet.
    You can go with boards with bigger spacing like other people have suggested. Or there is at least one supplier on ebay that sells smaller screw threads with 2.54mm spacing (i.e. 0.1" used in breadboards and prototype boards) for at least 14 columns -- you probably would want to use a prototype with soldered female headers, and attach these rails on the outside:


    Quote Originally Posted by EddieLeo View Post
    3. Given the apparent popularity of this display / touch screen, it seems that someone would have developed and published a set of common UI widgets for it, but I have not been able to find any. Is there a resource I have just not located? It's not a huge issue for me, as I am using the "opportunity" to develop my OOP skills and knowledge and already have a good start on a nice set of widgets (pushbuttons, slider, bar graphs, data display, etc).
    No idea.

    Quote Originally Posted by EddieLeo View Post
    4. With regard to item 3 programming, I have a really stupid question. Does code developed and put in a library format perform any more efficiently than the compiled code in the Arduino IDE? Is there any benefit to creating libraries other than for redistribution purposes and segmenting code for reuse? Is there a preferred (free) C compiler for developing libraries?
    You use exactly the same compiler (GCC) that is used for the Arduino .ino/.pde script. The only real difference is with the library, you have to write in straight C++. You don't get the Arduino pre-processing that 'simplifies' the C++ language. But it is rather handy to have your own set of libraries, that you reuse in each new project.

    Quote Originally Posted by EddieLeo View Post
    5. Is there a compiled list of various resources for Teensy related hardware somewhere? Sourcing stuff can be very time consuming when you aren't always sure what you are even looking for.
    Apologies if I am looking for quick and easy answers as opposed to doing extensive research. Like I said, I'm old - there are only so many days left. I'm just trying to keep the brain cells going as long as I can with this type of activity.
    Warning: More questions to come on a variety of topics. There's a lot to learn. Is this the right place?
    There is this list, but parts of it may not be up to date:


    But ask away, but do try to limit things to one main question per thread and use a subject header that describes what you are asking. This is to allow people to skip subjects they aren't interested in and quickly narrow down things for a suitable reply.

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