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Thread: 240x320 TFT display working fine now solid white permanently

  1. #1
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    240x320 TFT display working fine now solid white permanently

    i had the display working fine and started modifying the circuit and display to use the SD card. Plug everything back in and got only a white screen. Checked wiring, it is fine. Tried again, same issue, rewired again, same issue. Removed SD wires and returned wires to previous display only condition, still the white screen. I put in a new display after rewiring again, still the white screen. Did I blow the teens ? Using the ILI9341 library. Loaded graphicstest, still white screen. Advice welcome.

    Thank you.

  2. #2
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    Are you using 10k pull ups on the CS lines? Initializing the SD card before the display to be sure it is in SPI mode? Show us your wiring and code as it helps us to help you.

  3. #3
    Yep, when I run into this it's due to RST not being powered up correctly (some displays are finicky and require some extra steps). The RST needs to be high just slightly after the display is powered up

    1. is your RST pin on the display connected to 3v3 or an MCU pin? if not you can try connecting RST to a digital pin and changing your object creation call to
    ILI9341_t3 Display = ILI9341_t3(TFT_CS, TFT_DC, TFT_RST);
    )
    2. if RST is connected to 3v3 try adding a 1K resistor in series and a 10uf Cap to ground (connected between RST and ground). This will slow the charge to RST, hence letting the display power up first. These are the values I use, but you may need to change them

    Hope this helps.

  4. #4
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    Which Teensy are you using?
    Which code were you using and how was the display wired?
    I'm currently playing around with a 240x320 ILI9341-based display. First, I got it working on an Arduino Duemilanove and then on a Teensy++2. I'm currently trying to get it running on a T3.5. While doing this, I've noticed that if you use the UTFT library on Teensy3.x you have to choose between using ports B+D or Ports C+D. If you use C+D you cannot access the SD card.

    BTW. The display that I have requires both 5V and 3V3 but the display digital pins output 5V, which is why I'm trying to get it going on the 5V-tolerant Teensy 3.5.

    Pete

  5. #5
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    Thanks for the replies. I hadnít added any code for the SD when things went south. The current code and wiring was working fine with the display for sometime when this occurred. I have the RST pin wired to the 3V3 line. The display is powered from the teensy 3V3 line i do not have the SD card wires attached. I didnít use the pull up resistors as the display worked fine up until this failure. I noted that the pull ups were part of the modification to use the SD card. Since I have swapped out the display I fear it is a teensy 4 hardware issue. I will try the pull ups and the slow RST line suggestion.

  6. #6
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    Ooops. I appear to be using an older version of the display which was set up as a shield for Arduino UNO and used parallel data transfer rather than SPI.

    Pete

  7. #7
    a buck says its the RST line

  8. #8
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    RST Line

    Quote Originally Posted by KrisKasprzak View Post
    a buck says its the RST line
    The code you suggested was already in the program. I have RST tied to 3V3, but I will try the RC you suggested. However, I am still not clear why this work fine for hours and hours and then when I wired in the SD (no code to support) it went bad. Nor do I understand how the same code, no SD wires, and a new display are doing the same thing, given it was all working before. Time will tell. Thanks for the advice.

  9. #9
    Senior Member+ KurtE's Avatar
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    Sorry it is sometimes hard to help without seeing much of anything. Like the code or the wiring or... Which Teensy? Which version of Arduino...

    Yes you mentioned graphictest and you mentioned ILI9341, but for example is this the one PJRC sells or one that Adafruit sells or ??? Why that might matter, is for example Adafruit builds in things like Pull-up resistors and the like so for example you can leave the RST unconnected and it will likely work. Where as PJRC one is more basic version and you need to do something with the RST line.

    Likewise you mentioned adding SD connection? Again which one? how is it connected... Do you have Pull UP resistors on the CS pins? again Adafruit board may have these built in.

    If you don't have it. Then maybe CS pin is floating or LOW and it is also trying to process the SPI data, which could cause it to mess up.

    So if they don't have CS pins with PU resistors you can most of the time fix the issue.

    By before calling the begin or init functions for the display or SD... You first add some lines like:
    Code:
    pinMode(SD_CS, OUTPUT);
    digitalWrite(SD_CS, HIGH); // make sure it does not do SPI called on...
    Again which ILI9341 library are you using? Adafruit_ILI9341, or ILI9341_t3, or ILI9341_t3n or ???

    Why this matters are things like: ILI9341_t3 library will only work if both the DC pin and CS pin is on a hardware CS pin (on T3.x boards) On T4 that is relaxed as the CS pins work differently.

    So sorry for this shotgun like answer but maybe one of the pellets will hit the right target.

  10. #10
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    Teensy 4.0 and the Red TFT display (HiLetgo ILI9341 2.8" SPI TFT LCD Display Touch Panel 240X320 with PCB 5V/3.3V STM32)

    I used the ILI9341.t3 and graphictest that are under Teensy libraries and examples in the Arduino IDE. Like I said before these were working fine before the stuff hit the fan. I can still load and run graphictest and get the board info from the Serial Monitor even though the display is white. I have pull up resistors on DC, RST, and CS. I don't have the SD connected in anyway right now. I am focusing only on getting the display running correctly again. I will follow you advice when I attempt the SD function again, including replacing R1-R3 with 0-ohms which has been documented before in other areas of the forum.

    Thanks for your help.

  11. #11
    Senior Member+ KurtE's Avatar
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    You are welcome. Also at times like this, it might help if you posted a picture of your current setup. Maybe someone will see something like:
    you are off by one pin... Been there, or maybe MISO amd MOSI pins reversed (again been there).

    Or maybe the IO pins are not fully soldered in or ...

    Or maybe power issue? I don't remember if these have a built in Voltage regulator and if it needs +5v to go to the VIN pin? Again some of there documents are not overly clear from their instructions.
    So are you trying to supply it from VIN or 3.3v? Note: The one on PJRC mentions wanting 3.6-5v...

  12. #12
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    I experienced a similar problem when I tried to use my 2.2 and 2.8 inch displays (from PJRC) with my new Teensy 4.0. I also got a white screen. Both displays would work as expected on my 3.2 and 3.5 Teensy. The solution was to connect the Reset pin to the Teensy and reset the display during the initialization process by defining what pin is connected to reset.

  13. #13
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    Well I have tried it all and both displays are still white screen. The SPI is working as I can read information from the board. I think it's time to throw in the towel. I am still not sure how it went from working to not working, but I guess I will never know.

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