I am trying to get this display working on a Arduino Mega2560: https://newhavendisplay.com/content/specs/NHD-320240WG-BxTFH-VZ.pdf

Below how the display is supposed to be connected to an MPU (in my case the Arduino ATMega2560):

enter image description here

I used this code: https://support.newhavendisplay.com/hc/en-us/articles/4414078359191-NHD-320240WG-B-with-Arduino provided by Newhaven themselves.

I used pins 22 to 29 for PORTA (according to https://docs.arduino.cc/hacking/hardware/PinMapping2560):

enter image description here

When I upload and run the code, nothing happens.

The thing that I do not really get is the "negative voltage" of -25V, which is apparently built-in in this version of the display, but I measure nothing between ground and pin 17 of the display, when powered it through the Arduino's 5V on pins 1 and 2.

I also tried to power just the backlight with a separate source (takes about 140mA) or even the entire setup (total current 190mA, so the Arduino takes an extra 50mA).

  • A wiring diagram would be really helpful. Maybe pictures as well. Did you set up a pot between Vdd and Vee, which would go into the Vo? How are you measuring the voltages? What's the max current that the Mega can source? Also, how did you come up with pins 22-29 for PORTA? It says those are pins 71-78 (PAs)? Also, I have no clue why the example even sets up port C, if they don't end up actually doing anything with it.
    – Nick S.
    Nov 18 at 20:42
  • @NickS. I updated the question with extra information from the links I provided. About port C, those are the digital outputs 30 and further, which are used by the control pins. Nov 19 at 14:00
  • 1
    Ah, hm, but you don't see the -25V though? Yeah, I assumed that'd be included as well, but I'm just trying to establish a baseline for everything that's described in their datasheet as well. I want to verify the electronics work before we proceed to the code. But yeah, I'd probably even do an official support ticket--depends, if you're doing this for work, I'd for sure do it. I have seen manufacturers and companies provide incomplete documentations, have mistakes and/or design flaws, or I just messed up myself. No one knows the manufacturer's product better than themselves...one would hope :)
    – Nick S.
    Nov 20 at 15:25
  • 1
    Your other question is now being pushed by the system. It contained preexisting answers largely addressing what I have. I consider it a mistake for you to have opened two questions for what is probably the same issue. Unless you give indication soon that this issue should still be open and is not actually a duplicate, I'm going to vote to close it as a duplicate of the other. If you've already solved your problem you there you should have deleted this question. If you start yet another question, do not post without fixing the array issue.
    – timemage
    Nov 22 at 17:49
  • 1
    @timemage this question is mainly about the Vee thing. I was hoping somebody already is using this display and have some pointers. The other question is specifically about the memory thing and has nothing to do with the display. Nov 23 at 9:56


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Browse other questions tagged or ask your own question.