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  1. #21
    During 3 months after adding the serial resistors I caught garbled display only once (without the resistors display was garbled every few minutes).

    If I was designing a new controller board, I would further improve LCD interface, but there are a lot of other terrible things in cheap 3D printer electronics, like MOSFETs driven directly from controller outputs, endstops with NO switches, or electrolytic capacitors placed directly under hot stepper motor drivers.
    So taking into account all these potential problems, I would say that 1 LCD error during 3 months is acceptable for me.

  2. #22
    Senior Engineer
    Join Date
    Jun 2014
    Location
    Burnley, UK
    Posts
    1,664
    The whole world drives MOSFETs from micro outputs now. Good design it isn't, cheap it is.

  3. #23
    But the whole world doesn't use PWM with MOSFETs driven directly from MCU outputs...

  4. #24
    Engineer-in-Training
    Join Date
    Jun 2014
    Posts
    350
    My display only garbles, sometimes, when inserting/removing the SD card while powered on. One button push fixes it. I know it should be powered off.

    More interesting is that the other functions that the button controls sometimes takes repeated button pushes to activate; I know each push is working because it makes it's little click, but sometimes five pushes are needed for the function to activate.

  5. #25
    Quote Originally Posted by printbus View Post
    Interesting. Be sure to report back after a while to confirm whether or not the series termination resistors solved your garbled display problem. I'd try the fix myself, but I've eliminated the nibble transfer display as part of migrating to Smoothieboard on my i3v.

    Technically, the bulk of the benefit is likely obtained by adding the termination resistor in the E signal line to the display. IIRC, that is the signal that is pulsed to latch each nibble data transfer into the display module. Ringing on any other pins likely wouldn't matter as long as they're stable when the E pin is pulsed, but there's no reason the termination can't be added in all the data lines. Also note that some of the data lines (encoder, SD reader) on the two cables are driven by the smartpanel and not the ATMEGA2560.
    Printbus and ESS, I cannot say thanks enough to you both. I had already shielded the LCD ribbon of my ANET A8 but the screen still failed once every 3 min or so. I then installed only one 47 Ohm resistor directly on the LCD PCB in serial of the ENABLE signal and combined with the shielding connected to ground, it's now working very very well.
    I have not yet the feedback over a long print but definitely it helps a lot.
    But ENABLE+47Ohm alone or shielding alone is not enough (for me)
    ANET_LCD_solution.jpg

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