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Thread: Problems with display ST7735S and Teensy 4.0

  1. #1

    Problems with display ST7735S and Teensy 4.0

    I've successfully connected display ST7735S to Teensy 4.0 this way:
    GND -> GND
    VCC -> 5V
    SCL -> SCK (13th pin)
    SDA -> MOSI (11th pin)
    RES -> 8th pin
    DC -> 9th pin
    CS -> CS (10th pin)

    However, there is no image on display; only backlight.
    I used a Teensy library ( especially written for this type of displays to be connected with Teensy.
    I used a following code:

  2. #2
    Senior Member+ KurtE's Avatar
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    Jan 2014
    Sorry would suggest using different library, my guess is that one is ancient as it talked about being optimized for Teensy 3.1...

    Two alternatives:
    Use the more current Adafruit library: You can either download it directly from their github:
    Or you can use the Adruino library manager for it.

    Or you can use the library that is installed with Teensyduino:

    Again the later one is included with the Teensyduino releases

  3. #3
    I've just tried both these libraries and it failed, unfortunately.
    Here's my code for the 1st ( library attempt:
    And here's for the 2nd: (

  4. #4
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Which Display are you using? It looks different than the Adafruit one.

    I have played around with the Adafruit one, but it could be configured differently, that is the controller can handle so many pixels and this display only shows a portion of it, so the question may be what portion of memory does it use...

    It looks like a few of them that for example Amazon sells like:

    Ordered 2 from Ebay: That look same, ship from US so should be here within week...
    Last edited by KurtE; 08-28-2021 at 09:54 PM.

  5. #5
    In this case, as in other similar ones, you have to connect wire by wire again, you have to check the continuity to ensure that any of them is not broken.

    You also have to check the welds on the screen pins, sometimes there are traces of some protection wax that prevent the correct connections between the screen PCB and the pin strips. I don't have that screen on hand, but I have a TFT ST7735 with a touch panel, I have connected it to a teensy 4 and it works.

    Click image for larger version. 

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    Library: ST7735_t3

  6. #6
    Yes, the display I am using looks the same way to which you ordered.

  7. #7
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Sorry I received the TFT from ebay and just soldered up the pins. and connected it up to a T4

    I loaded up Graphic test in the ST7735_t3 library.

    Edited it to say I am using
    define TFT_DC   9 
    #define TFT_CS   10  
    #define TFT_RST  8
    ST7735_t3 tft = ST7735_t3(TFT_CS, TFT_DC, TFT_RST);
    And the graphic test appears to work fine for me on this display
    Click image for larger version. 

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