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):
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):
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).