For those having trouble with this display like I did, the first thing you should try is adjust the blue potentiometer for contrast. Initially, my screen was just lit up, no characters or anything on it. I thought it wasn't displaying anything.
I had spent a few hours trying different codes, and was even about to do some hardware modifications, but fortunately I tried the contrast adjustment first, and after about 15 seconds of turning the potentiometer, I started seeing the characters and I was really excited.
I know I'm a little late on this thread, but I hope that I will save someone all the trouble I had to go through until I realized what was the problem.
