ESP32 MQTT Library sample application

• Dependency library: https://github.com/tuanpmt/espmqtt

Prerequire

• ESP32 compiler:
• ESP-IDF: https://github.com/espressif/esp-idf

Compile

git clone --recursive https://github.com/tuanpmt/esp32-mqtt

Run command make menuconfig to change SERIAL PORT configuration and the options at Component config -> MQTT :

• CONFIG_MQTT_PROTOCOL_311: default is yes
• CONFIG_MQTT_SECURITY_ON: default is yes
• CONFIG_MQTT_PRIORITY: default 5
• CONFIG_MQTT_LOG_ERROR_ON: defaut is yes
• CONFIG_MQTT_LOG_WARN_ON: defaut is yes
• CONFIG_MQTT_LOG_INFO_ON: defaut is yes
• CONFIG_MQTT_RECONNECT_TIMEOUT: defaut is 60 seconds
• CONFIG_MQTT_QUEUE_BUFFER_SIZE_WORD: default is 1024 (4096 bytes)
• CONFIG_MQTT_BUFFER_SIZE_BYTE: default is 1024 bytes
• CONFIG_MQTT_MAX_HOST_LEN: default is 64 bytes
• CONFIG_MQTT_MAX_CLIENT_LEN: default is 32 bytes
• CONFIG_MQTT_MAX_USERNAME_LEN: default is 32 bytes
• CONFIG_MQTT_MAX_PASSWORD_LEN: default is 32 bytes
• CONFIG_MQTT_MAX_LWT_TOPIC: default is 32 bytes
• CONFIG_MQTT_MAX_LWT_MSG: default is 32 bytes

Copy main/include/user_config.sample.h to main/include/user_config.local.h and provide WIFI_SSID, WIFI_PASS

make && make flash

Usage

 mqtt_settings settings = {
    .host = "192.168.0.1",  // or domain, ex: "google.com",
    .port = 1883,
    .client_id = "mqtt_client_id", 
    .username = "user",
    .password = "pass",
    .clean_session = 0, 
    .keepalive = 120, //second
    .lwt_topic = "/lwt",    // = "" for disable lwt, will don't care other options
    .lwt_msg = "offline",
    .lwt_qos = 0,
    .lwt_retain = 0,
    .connected_cb = connected_cb, // trigger when client connected to broker with valid infomations
    .disconnected_cb = disconnected_cb, //trigger when client disconnect from broker
    .reconnect_cb = reconnect_cb, //trigger when client reconnect - not implement yet
    .subscribe_cb = subscribe_cb, //trigger when client subscribe a topic successful 
    .publish_cb = publish_cb, //trigger when client publish data to channel successful 
    .data_cb = data_cb //trigger when client receive data from channel has subscribed
};

mqtt_client *client = mqtt_start(&settings);

Data receive from channel subscribed:

void data_cb(void *self, void *params)
{
    mqtt_client *client = (mqtt_client *)self;
    mqtt_event_data_t *event_data = (mqtt_event_data_t *)params;
}

typedef struct mqtt_event_data_t
{
  char* topic;  //point to topic 
  char* data; //point to data
  uint16_t topic_length;
  uint16_t data_length; //current packet length
  uint16_t data_offset; //current packet offset
  uint16_t data_total_length; //total packet length
} mqtt_event_data_t;

Todo list

• Create MQTT task server all protocol defined - Support subscribing, publishing, authentication, will messages, keep alive pings and all 3 QoS levels (it should be a fully functional client).
• Support mbedtls for SSL connection
• Write document

Progress:

• Can connect, subscribe, support queue for subscribe, support lwt msg
• Direct send keepalive packet
• Can publish
• Can receive and process publish qos 0
• Can receive and process publish qos 1 and 2
• Implement all events

License

Apache 2.0