3 Run states

An ExpressLink module operates as a state machine that moves through a number of internal states (see figure 2 for a partial representation).

Figure 2 - ExpressLink internal states diagram (partial)

 

The application or host processor is presented with a small command set that is independent from the connectivity solution offered by the specific module (such as ethernet, cellular, and Wi-Fi).

The serial interface is designed to be stateless, with all interactions initiated exclusively from the host side. When an asynchronous event occurs (a message is received or an internal error condition occurs), the ExpressLink module queues the event and flags its availability to the host via the Event pin. A host can choose to ignore the Event pin (to conserve I/Os) and instead poll the module periodically. (See 7.2 Event handling commands.)