File syn_mqtt.h¶

Lightweight MQTT 3.1.1 client.

#include "../common/syn_defs.h"
#include "../port/syn_port_socket.h"
#include "../pt/syn_pt.h"
#include "../sched/syn_task.h"

Classes¶

Type	Name
struct	SYN_MqttClient MQTT client context structure.

Public Types¶

Type	Name
enum	SYN_MqttRxPhase Non-blocking packet reception states.
enum	SYN_MqttState MQTT client connection states.

Public Functions¶

Type	Name
SYN_Status	syn_mqtt_init (SYN_MqttClient * client, const char * host, uint16_t port, const char * client_id, const char * username, const char * password, uint16_t keep_alive_s, uint8_t * rx_buf, size_t rx_buf_size, uint8_t * tx_buf, size_t tx_buf_size) Initialize the MQTT client.
SYN_Status	syn_mqtt_ping (SYN_MqttClient * client) Transmit an explicit MQTT PINGREQ packet.
SYN_Status	syn_mqtt_publish (SYN_MqttClient * client, const char * topic, const void * payload, size_t len, uint8_t qos, bool retain) Publish a message to a topic.
SYN_Status	syn_mqtt_subscribe (SYN_MqttClient * client, const char * topic, uint8_t qos) Subscribe to a topic.
SYN_PT_Status	syn_mqtt_task (SYN_PT * pt, SYN_Task * task) Cooperative task for driving the MQTT client.

Public Types Documentation¶

enum SYN_MqttRxPhase¶

Non-blocking packet reception states.

enum SYN_MqttRxPhase {
    SYN_MQTT_RX_IDLE,
    SYN_MQTT_RX_REMAINING_LEN,
    SYN_MQTT_RX_PAYLOAD,
    SYN_MQTT_RX_DISCARD
};

enum SYN_MqttState¶

MQTT client connection states.

enum SYN_MqttState {
    SYN_MQTT_DISCONNECTED,
    SYN_MQTT_CONNECTING,
    SYN_MQTT_CONNECTED
};

Public Functions Documentation¶

function syn_mqtt_init¶

Initialize the MQTT client.

SYN_Status syn_mqtt_init (
    SYN_MqttClient * client,
    const char * host,
    uint16_t port,
    const char * client_id,
    const char * username,
    const char * password,
    uint16_t keep_alive_s,
    uint8_t * rx_buf,
    size_t rx_buf_size,
    uint8_t * tx_buf,
    size_t tx_buf_size
)

Configures broker destination, client ID, authentication credentials, keep-alive timing parameters, and network packet buffers.

Parameters:

client Pointer to client context.
host Broker network address string.
port Broker port number.
client_id MQTT client identity string.
username Authentication username (or NULL).
password Authentication password (or NULL).
keep_alive_s Keep-alive timeout parameter in seconds.
rx_buf Receive buffer storage.
rx_buf_size Receive buffer capacity.
tx_buf Transmit buffer storage.
tx_buf_size Transmit buffer capacity.

Returns:

SYN_OK on successful configuration, or error parameter code.

function syn_mqtt_ping¶

Transmit an explicit MQTT PINGREQ packet.

SYN_Status syn_mqtt_ping (
    SYN_MqttClient * client
)

Note: PINGREQ packets are sent automatically by syn_mqtt_task based on the configured keep_alive_s interval. This function allows manual pinging on demand.

Parameters:

client Pointer to client context.

Returns:

SYN_OK on success, SYN_ERROR if not connected or transmit failed.

function syn_mqtt_publish¶

Publish a message to a topic.

SYN_Status syn_mqtt_publish (
    SYN_MqttClient * client,
    const char * topic,
    const void * payload,
    size_t len,
    uint8_t qos,
    bool retain
)

Non-blocking publish command. For QoS 0, queued directly. For QoS 1, tracks acknowledgement state.

Parameters:

client Pointer to client context.
topic Topic name to target.
payload Data payload to send.
len Payload size in bytes.
qos Quality of service level (0 or 1).
retain Retain flag on broker.

Returns:

SYN_OK on queued, or error status if payload bounds exceeded.

function syn_mqtt_subscribe¶

Subscribe to a topic.

SYN_Status syn_mqtt_subscribe (
    SYN_MqttClient * client,
    const char * topic,
    uint8_t qos
)

Formats and queues a subscription request for transmission.

Parameters:

client Pointer to client context.
topic Topic filter string.
qos Requested quality of service.

Returns:

SYN_OK on success.

function syn_mqtt_task¶

Cooperative task for driving the MQTT client.

SYN_PT_Status syn_mqtt_task (
    SYN_PT * pt,
    SYN_Task * task
)

Yields during connection, socket polling, keep-alive pinging, and packet parsing loops. Runs within the cooperative scheduler context.

Parameters:

pt Cooperative protothread handle.
task Corresponding task control block.

Returns:

PT_WAITING or PT_EXITED status.

The documentation for this class was generated from the following file src/syntropic/net/syn_mqtt.h