Arduino: How to control a HD44780 based character LCD

Many characters LCD displays use so called HD44780 based protocol on interface. This is more like standard but i recommend to check datasheet from vendor. There can be small modifications and/or difference in timing. Especially timing is important. If communication rate is too quick, then LCD drop data or misbehave depending on internal state. I recommend to check busy flag if possible. If not then correct delay should be applied between commands. Result of commands can be checked via LCD Simulator prior to programing MCU. For example i like this one: DjLCDSIM.