I have a Black on yellow 1602 LCD mounted in an enclosure.
The LCD has an I2C backpack and is connected to a Mega.
I have only been using the display for the last 2 to 3 months during testing and not for extended periods at a time.
When I start running the sketch, the letters are crisp and I can read the displayed text at an angle.
After a while (minutes) the black print becomes washed out and the contrast reduces to the point that I can only read the text front-on and from a very close range.
If I restart the sketch, it starts off looking good, then degrades as above.
Sometimes when I prod and poke the display, there a temporary or partial improvement in contrast.
Anybody had this kind of issue and found a fix?
Or is it time to bury my display?
I think I may have found the culprit... seems the laptop USB port does not make very good contact with the cable.
Well, that is one possibility, but the other is that the current draw is close to the limiting factor in the USB power controller (in the PC) and it is going into partial thermal shutdown.
That is what my desktop does here - tends to droop to about 4.5 V or less but if disconnected for a while it recovers. The contrast is very dependent on the supply voltage.
It was definitely a bad contact.
I got so ticked off with it today, I grabbed a pair of pliers and squeezed the opening of the USB cable connector closed a bit. One port is still a bit of an issue, but in the other port it makes better contact and I now have a crisp display.
Took the pliers to the cable on my mouse as well - muuuuuuuuch better