iLCD panels can be controlled via RS232 (also RS422 and RS485), USB, SPI and I²C as well as TCP/IP using the optional Ethernet interface board.
However, use of the serial SPI and I²C protocols is only recommended if there is no RS232 connection available. The RS232 is the fastest of the serial interfaces and is intended for communication between two equitable devices. SPI and I²C on the other hand are master-slave protocols, hence the iLCD panel is not able to send data to the application unless actively queried. Therefore, responses and asynchronous data from the iLCD panel has to be polled or an additional wire must be used for signaling data availability.
It is possible to connect more than one of the interfaces simultaneously. Since all ports share a single input buffer, it must be ensured that the interfaces don't interrupt each other mid-command. The outgoing data is always sent to the port the last incoming byte was received from, switching is done as soon as a byte from another interface enters the input buffer.
The following chapters describe the different ways to control iLCD panels:
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