kaich1n / esp-mqtt

MQTT component for esp-idf projects based on the lwmqtt library

esp-mqtt

MQTT component for esp-idf projects based on the lwmqtt library

This component bundles the lwmqtt client and adds a simple async API similar to other esp networking components. Secure connections are supported via the mbedTLS library.

Installation

You can install the component by adding it as a git submodule:

git submodule add https://github.com/256dpi/esp-mqtt.git components/esp-mqtt
git submodule update --init --recursive

The component will automatically enable the LWIP receive buffers.

PlatformIO

You need to set CONFIG_LWIP_SO_RCVBUF=y manually in sdkconfig.

Example

An example can be found here: https://github.com/256dpi/esp-mqtt/blob/master/test/main/main.c.

Notes

If you are sending large messages, setting CONFIG_USE_ONLY_LWIP_SELECT=y might prevent some issues.

API

Initialize the component once by passing the necessary callbacks:

void esp_mqtt_init(esp_mqtt_status_callback_t scb, esp_mqtt_message_callback_t mcb,
                   size_t buffer_size, int command_timeout);

Enable secure connection using TLS:

bool esp_mqtt_tls(bool enabled, bool verify, const uint8_t * ca_buf, size_t ca_len);

Optionally, configure a Last Will and Testament:

void esp_mqtt_lwt(const char *topic, const char *payload, int qos, bool retained);

When the WiFi connection has been established, start the process:

bool esp_mqtt_start(const char *host, const char *port, const char *client_id,
                    const char *username, const char *password);

When the client has connected, interact with the broker:

bool esp_mqtt_subscribe(const char *topic, int qos);
bool esp_mqtt_unsubscribe(const char *topic);
bool esp_mqtt_publish(const char *topic, uint8_t *payload, size_t len, int qos, bool retained);

If the WiFi connection has been lost, stop the process:

void esp_mqtt_stop();