[roland35]

One bug that I encounter many times in projects using similar displays is not giving enough time for commands to process. Often times what works while testing may work 99.99% of the time but that 0.01% it doesn't work could end up as an incorrect character or even an invalid command!

A recent bug I figured out later was sending a certain graphical character matched the "display off" command, and the command bit was not being set quickly enough due to a long cable connection. Once the display off command was sent the screen would not turn back on...

The best way to solve this is to implement firmware to read the status flag of the display, if you are lucky enough to have one. I find this helps a lot with all types of sensors and other external interfaces, send the data and read it back. You will thank yourself that 0.01% of the time it didn't work!