The Wi-Fi module can send to the micro-controller some system messages to inform it about the module state or about important events. When the WiFi module is powered-up (after 3 seconds) a message like the following one will be sent indicating that the system is ready:

{miuPanel STARTED – Ver. XXYYYZ – Fri Jul 10 11:13:03 CEST 2015}
$RES

The other messages that can be sent from the Wi-Fi module are:

$ONLINE to inform that a user has connected its mobile to the system

$OFFLINE to inform that a user has disconnected its mobile from the system