It is quite easy to control the LED panel. We can simply set bits which will cause some of the segments to light up. In the case off the LCD things are quite different. The LCD is an intelligent device, in that its controller is a microprocessor which must be given commands to make it do things for us. We must therefore go through a routine of sending a command to the LCD, waiting for it to complete and then sending the next.

To achieve communication we will work at two levels:

  • Sending a value to the LCD

  • Using the ability to send a value to construct and send commands and data to it.

The LCD takes time to react to an instruction so we will need to make sure that we don't overwhelm the device with commands. If we do this the display will simply lock up.