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Thread: Teensy 4.1 with TFT Touchscreen ILI9341 and QVgaTest_Touch Board

  1. #1
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    Teensy 4.1 with TFT Touchscreen ILI9341 and QVgaTest_Touch Board

    I have searched the boards and don't think anyone has asked this question. I am new so please forgive me if I missed it somewhere. I am also not an electronics expert and just a hobbiest. So any guidance is appreciated.

    I am purchasing a Teensy 4.1 board. I am hoping to use it for a custom game controller. I would like to use a touchscreen as a custom display screen. On the PJRC store page for the Color 320x240 TFT Touchscreen using the ILI9341 Controller Chip (https://www.pjrc.com/store/display_ili9341_touch.html), it shows several Teensy versions including a picture of a 3.2 and what appears to be a 4.1 connected to an interface board referred to as the "purple test board" which links to the "qvgatest_touch" board (https://oshpark.com/shared_projects/TG395I75) by @PaulStoffregen.

    I am unclear about the purpose of the interface board other than to provide a connection between the Teensy and the ILI9341. I see a power connector, a line voltage regulator, and a few resistors. I understand the display uses 3.3 v so I was thinking maybe the board electronics provide some regulated 3.3v output, but the text on the display's page at the PJRC store says:

    "This ILI3941 display works well with Teensy 4.0 and 4.1, using the standard connections shown in the table."

    Outside of 1 resistor mentioned in the table for the LED, do I need the board or can I directly connect to the pins on the Teensy 4.1 to the ILI9341 as indicated? Or is the qvgatest_touch board providing another function? Maybe for an earlier Teensy? If it is needed or recommended, can someone explain what it does?

    Any help is appreciated.

  2. #2
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by ShogunBaker View Post
    I am unclear about the purpose of the interface board other than to provide a connection between the Teensy and the ILI9341.
    Indeed that is all it does, just connect Teensy to the display.


    Outside of 1 resistor mentioned in the table for the LED, do I need the board or can I directly connect to the pins on the Teensy 4.1 to the ILI9341 as indicated?
    You don't need that circuit board. It's just wires and 1 resistor. But it sure is convenient if you retest the library every several months, as I do...

  3. #3
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    Quote Originally Posted by PaulStoffregen View Post
    Indeed that is all it does, just connect Teensy to the display.




    You don't need that circuit board. It's just wires and 1 resistor. But it sure is convenient if you retest the library every several months, as I do...
    No doubt the board is convenient. I will just be making other connections so I plan to redesign a new board to make the connections. The wording on the PJRC website essentially saying you can directly connect the 4.0/4.1 board to the display but then showing a picture of a 4.0/4.1 connected to your board with additional electrical components then to the display is confusing.

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