Weired display with Megatronics V3.1

Hi there,
I hope you can help me.

In my 3d printer there was a megatronics v3.0 board. Unfortunately it broked and i ordered a new one.
Now i have a brand new megatronics v3.1 board.
However with the old firmware, with worked totally fine with the 3.0 - Board i get this on the display:

When i loaded the megatronics test-firmware to the board it shows the temperature and everything is fine.

I cant find a problem, do can you help me please?

Best regards


  • I assume both boards are pin compatible, so would as well expect same thing to work. Maybe with rewiring some heater cables came closer to display cable? That breaks my display every time, but it would work at least until heaters are enabled.

    You can also try

    That will reinit display every second. Helps especially if it works for a while and then gets garbage.
  • Hi,

    Thank you for your answer.
    Unfortunately your solution didn't work :-(
    Yes the boards are pin compatible.
    According to the datasheet, the only difference between the boards are:
             -SD card detect support on A2/D57
             -I2C now kept active even without power on the board

    The strange thing is, that, with repetier-host, i am unable to control the printer. Like home a axis, for example.
    But when i sent the printer a M115 command, i will get an normal response.

    What could that be?

    Best regards,

  • Not sure what they mean with that. From pin definition in their datasheet I see
    A2/D56 SDOUT
    A3/D57 X axis direction

    and it is D57 that is x motor direction - always was.

    Last thing I can think of is delay if lcd is slow. In DisplayList.h you see for each controller a

    #define UI_DELAYPERCHAR 50

    That sets the delay in us between 2 chars send to controller. You could increase that to 100 and see if it helps. But 50 is normally enough for all.

    For your other problem try disabling display first so you know it does not interfere.
    One common problem is a automount loop, but you would see that in log when connected.
    Check M119 and consider that new firmware has an option that moves are only allowed after homing.
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