Channels

In the Asset Tracker Template, each module declares and defines a channel using zbus macros. For example, in the app/src/modules/network/network.h file, the Network module declares the network_chan channel:

/* Channels provided by this module */
ZBUS_CHAN_DECLARE(
    network_chan
);

The channel is defined in app/src/modules/network/network.c:

/* Define channels provided by this module */
ZBUS_CHAN_DEFINE(network_chan, /* Channel name, derived from module name */
        struct network_msg,    /* Message data type */
        NULL,                  /* Optional validator function */
        NULL,                  /* Optional pointer to user data */
        ZBUS_OBSERVERS_EMPTY,  /* Initial observers */
        ZBUS_MSG_INIT(0)       /* Message initialization */
);

In the Asset Tracker Template, the fields of the ZBUS_CHAN_DEFINE macro are populated in a similar way across modules:

• Channel name: The name of the channel, derived from the module name.
• Message data type: The data type used to hold message data. The name comes from the channel name.
• Validator function: Not used.
• User data: Not used.
• Initial observers: The initial observer list is empty. Observers are added in the relevant modules later.
• Message initialization: The initial value stored in the channel. This field is not used, so it is set to ZBUS_MSG_INIT(0).