[help request]How to send and receive stuff? about esp-mqtt HOT 6 CLOSED

@souxx and @wdouglas1999
Declare mqttClient as global variable and use it

// global declaration
esp_mqtt_client_handle_t mqttClient;

// initialize
esp_mqtt_client_config_t mqtt_cfg = {
...
...
...};

mqttClient = esp_mqtt_client_init(&mqtt_cfg);
esp_mqtt_client_start(mqttClient);

// subscribe
esp_mqtt_client_subscribe(mqttClient, topic, qos);

// publish
esp_mqtt_client_publish(mqttClient, topic, data, dataLength, qos, retain);

Hope this is helpful

from esp-mqtt.

Hello, thanks for your work, however I still cannot understand how to to receive a message from a subscribed topic. Do I have to set a callback function? A commented exemple of publishing and receiving a message could be real helpful. Thanks!

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@ DarioB92,

I ended up using the example following example code on github.

https://github.com/jessebraham/esp32-mqtt-client/blob/master/main/esp32-mqtt-client.c

I hope it will help you.

from esp-mqtt.

@DarioB92 mqtt_event_handler is the required call back you are talking about and it is already set up. Whenever any message is available for subscribed topic MQTT_EVENT_DATA event will occur.

case MQTT_EVENT_DATA:
ESP_LOGI(TAG, "MQTT_EVENT_DATA");
printf("TOPIC=%.*s\r\n", event->topic_len, event->topic);
printf("DATA=%.*s\r\n", event->data_len, event->data);
break;

This will give you all required data regarding the received message. If you have basic knowledge of mqtt protocol, I think, the examples given in the repo are self-explanatory. You just need to try them.

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@souxx,
Good day,
Have you managed to figure out how to subscribe and publish massages yet? I would also like a basic example of how to do this.

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Closing this older issue, as it seems it has been answered. Please feel free to reopen or raise a new one if it's not the case.

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