I have a couple of these LCDs which I bought a few years ago and never used. Now I am trying to see if I can get them to work with an Arduino.
I know from reading elsewhere that the -H (hot) version is a PITA because it apparently needs a small negative voltage on the contrast pin unless the device is warm - but that's not the subject of this question
My problem is that I have never used anything like this before and I don't know what to expect.
I had assumed that if I connect it to 5v and GND (and nothing else) there will be some sign of life - for example barely visible background squares where the character positions are, or just a flicker as it initializes itself. However when I connect it there is absolutely no sign of life, with or without the backlight on and regardless of the contrast setting.
If what I see (nothing!) is perfectly normal I will assume there is a programming issue and pursue that.
The experience of someone who has used any variety of these 1602 displays would be appreciated.
Edit to add ...
I discovered I needed a higher negative voltage on the contrast pin (3). It works fine if I use a 1.5v AA cell to create -1.5volts. Previously I had been using 2 diodes in series to lift the normal ground 0.8v above the contrast pin, but that wasn't enough.
And, for the benefit of others, with the correct contrast voltage the display is visible with just power, ground and contrast connected to the device.