Configurations

Configurations of the MQTT Agent.

configpagestyle

Configuration settings are C preprocessor constants. They can be set with a #define in the config file (core_mqtt_config.h) or by using a compiler option such as -D in gcc. The MQTT Agent uses the same configuration file as coreMQTT.

MQTT_AGENT_MAX_OUTSTANDING_ACKS

The maximum number of pending acknowledgments to track for a single connection.

Note

The MQTT agent tracks MQTT commands (such as PUBLISH and SUBSCRIBE) th at are still waiting to be acknowledged. MQTT_AGENT_MAX_OUTSTANDING_ACKS set the maximum number of acknowledgments that can be outstanding at any one time. The higher this number is the greater the agent's RAM consumption will be.

Possible values: Any positive integer up to SIZE_MAX.
Default value: 20

MQTT_AGENT_MAX_EVENT_QUEUE_WAIT_TIME

Time in milliseconds that the MQTT agent task will wait in the Blocked state (so not using any CPU time) for a command to arrive in its command queue before exiting the blocked state so it can call MQTT_ProcessLoop().

Note

It is important MQTT_ProcessLoop() is called often if there is known MQTT traffic, but calling it too often can take processing time away from lower priority tasks and waste CPU time and power.

Possible values: Any positive 32 bit integer.
Default value: 1000

MQTT_AGENT_FUNCTION_TABLE

An array of function pointers mapping command types to a function to execute. Configurable to allow a linker to remove unneeded functions.

Note

This array controls the behavior of each command. Altering the array would allow a linker to discard unused MQTT functions if desired. The size of this array MUST equal NUM_COMMANDS and the order MUST correspond to MQTTAgentCommandType_t commands if not using C99 designated initializers. If any function is desired not to be linked, it may be set to MQTTAgentCommand_ProcessLoop or a custom function matching an MQTTAgentCommandFunc_t prototype.

Default value:

{
    [ NONE ]        = MQTTAgentCommand_ProcessLoop,
    [ PROCESSLOOP ] = MQTTAgentCommand_ProcessLoop,
    [ PUBLISH ]     = MQTTAgentCommand_Publish,
    [ SUBSCRIBE ]   = MQTTAgentCommand_Subscribe,
    [ UNSUBSCRIBE ] = MQTTAgentCommand_Unsubscribe,
    [ PING ]        = MQTTAgentCommand_Ping,
    [ CONNECT ]     = MQTTAgentCommand_Connect,
    [ DISCONNECT ]  = MQTTAgentCommand_Disconnect,
    [ TERMINATE ]   = MQTTAgentCommand_Terminate
}