MQTT helper

This library simplifies Zephyr MQTT API and socket handling.

Configuration

To use the MQTT helper library, enable the CONFIG_MQTT_HELPER Kconfig option.

Additionally, configure the following options as per the needs of your application:

API documentation

Header file: include/net/mqtt_helper.h
Source file: subsys/net/lib/mqtt_helper/mqtt_helper.c
group mqtt_helper

Convenience library that simplifies Zephyr MQTT API and socket handling.

Typedefs

typedef bool (*mqtt_helper_on_all_events_t)(struct mqtt_client *const client, const struct mqtt_evt *const event)

Handler invoked for events that are received from the MQTT stack. This callback handler can be used to filter incoming MQTT events before they are processed by the MQTT helper library.

Param client:

Pointer to the MQTT client instance.

Param event:

Pointer to the MQTT event.

Retval 0:

if the event is handled by the caller. No further processing of the MQTT event will be carried out by the MQTT helper library.

Retval 1:

if the MQTT helper library should continue to process the event after the handler returns.

typedef void (*mqtt_helper_on_connack_t)(enum mqtt_conn_return_code return_code, bool session_present)
typedef void (*mqtt_helper_on_disconnect_t)(int result)
typedef void (*mqtt_helper_on_publish_t)(struct mqtt_helper_buf topic_buf, struct mqtt_helper_buf payload_buf)
typedef void (*mqtt_helper_on_puback_t)(uint16_t message_id, int result)
typedef void (*mqtt_helper_on_suback_t)(uint16_t message_id, int result)
typedef void (*mqtt_helper_on_pingresp_t)(void)
typedef void (*mqtt_helper_on_error_t)(enum mqtt_helper_error error)

Enums

enum mqtt_state

Values:

enumerator MQTT_STATE_UNINIT
enumerator MQTT_STATE_DISCONNECTED
enumerator MQTT_STATE_TRANSPORT_CONNECTING
enumerator MQTT_STATE_CONNECTING
enumerator MQTT_STATE_TRANSPORT_CONNECTED
enumerator MQTT_STATE_CONNECTED
enumerator MQTT_STATE_DISCONNECTING
enumerator MQTT_STATE_COUNT
enum mqtt_helper_error

Values:

enumerator MQTT_HELPER_ERROR_MSG_SIZE

The received payload is larger than the payload buffer.

Functions

int mqtt_helper_init(struct mqtt_helper_cfg *cfg)

Initialize the MQTT helper.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

int mqtt_helper_connect(struct mqtt_helper_conn_params *conn_params)

Connect to an MQTT broker.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

int mqtt_helper_disconnect(void)

Disconnect from the MQTT broker.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

int mqtt_helper_subscribe(struct mqtt_subscription_list *sub_list)

Subscribe to MQTT topics.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

int mqtt_helper_publish(const struct mqtt_publish_param *param)

Publish an MQTT message.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

int mqtt_helper_deinit(void)

Deinitialize library. Must be called when all MQTT operations are done to release resources and allow for a new client. The client must be in a disconnected state.

Return values:

  • 0 – if successful.

  • -EOPNOTSUPP – if operation is not supported in the current state.

Returns:

Otherwise a negative error code.

struct mqtt_helper_buf
#include <mqtt_helper.h>

Public Members

char *ptr

Pointer to buffer.

size_t size

Size of buffer.

struct mqtt_helper_cfg
#include <mqtt_helper.h>
struct mqtt_helper_conn_params
#include <mqtt_helper.h>