I have an Adafruit version of the HX8357 480x320 display attached to a Mega2560 ProMini, which to the best of my knowledge is an accurate replica of the Mega.
I have the touch screen function and the graphics function implemented, and they work correctly, so there seems to be nothing wrong with the board or wiring.
The problem is that the screen, although readable, is very faded. If I power the display from the 5 v. pin on the Mega, the display is faded. With that arrangement, the voltage to the Vin pin on the display is 4.3 volt. If, alternatively, I power both the Mega and the display from a standalone 5 v. power supply, the voltage reads 5.01 volts, and the the display is entirely white (all backlight, no image).
I have checked all power connections, and they are all solid.
Does anybody have a clue as to what causes this? Also. if I drop the voltage to the display to 3.3 v., can I still directly input the 5 v. signals from the Mega?