3.4.1 Asynchronous Events

Some APIs in the ATWINC15x0 host driver are synchronous function calls, where the result is ready by the return of the function. However, most API functions in the ATWINC15x0 host driver are asynchronous. This means that when the application calls an API to request a service, the call is non-blocking and returns immediately, before the requested action is completed. When completed, a notification is provided in the form of a HIF protocol message from the WINC firmware to the host which, in turn, is delivered to the application via a callback¹ function. Asynchronous operation is essential when the requested service such as Wi-Fi connection may take significant time to complete. In general, the ATWINC15x0 firmware uses asynchronous events to signal the host driver about status change or pending data.

The HIF uses push architecture where the data and events are pushed from the ATWINC15x0 firmware to the host MCU in a First-Come First-Served (FCFS) manner. For instance, the host MCU application has two open sockets: socket 1 and socket 2. If the ATWINC15x0 receives socket 1 data followed by socket 2 data, then HIF delivers socket data in two HIF protocol messages in the order in which it is received. HIF does not allow reading socket 2 data before socket 1 data.