en:reference:mqtt

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en:reference:mqtt [2017/10/30 11:28] – kniwwelinoen:reference:mqtt [2018/07/17 17:46] (current) – [void MQTTconnectMATRIX()] kniwwelino
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 +====== Messaging / MQTT ======
 +
 +===== API =====
 +
 +==== void MQTTsetGroup(String group) ====
 +Sets the MQTT group where all messages are sent and all subscriptions are done.
 +
 +Can be used to easily separate different applications/users/groups
 +
 +e.g. specify one group per game or one group per boards playing in the same game.
 +
 +
 +==== void MQTTonMessage(void (cb)(String &topic, String &message)) ====
 +Sets the callback function that is called one a MQTT message is received for one of the subscribed topics.
 +
 +needs a callback function with signature:
 +
 +''topic - String topic on which the message was received\\
 +message - String content of the received message.''
 +
 +
 +==== boolean MQTTpublish(const char topic[], String message) ====
 +Publishes/sents a message to the specified MQTT topic.
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string.
 +
 +''topic - topic to which the message will be sent\\
 +message - content of the message.''
 +
 +     
 +==== boolean MQTTpublish(String topic, String message) ====
 +Publishes/sents a message to the specified MQTT topic.
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string.
 +
 +''topic - topic to which the message will be sent\\
 +message - content of the message.''
 +
 +
 +==== boolean MQTTsubscribe(const char topic[]) ====
 +Subscribes to the specified MQTT topic. Once a message is received for a subscribed topic, the MQTTonMessage callback is called.
 +
 +If an MQTT group is set, the topic is automatically preceded with this group string.
 +see https://www.hivemq.com/blog/mqtt-essentials-part-5-mqtt-topics-best-practices for more information on topic subscriptions.
 +
 +''topic - topic to subscribe to''
 +
 +==== boolean MQTTsubscribe( String s_topic) ====
 +Subscribes to the specified MQTT topic. Once a message is received for a subscribed topic, the MQTTonMessage callback is called.
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string.
 +see https://www.hivemq.com/blog/mqtt-essentials-part-5-mqtt-topics-best-practices for more information on topic subscriptions.
 +
 +''topic - topic to subscribe to''
 +
 +==== boolean MQTTunsubscribe(const char topic[]) ====
 +Unsubscribes from the specified MQTT topic.
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string.
 +
 +''topic - topic to unsubscribe from''
 +
 +==== void MQTTconnectRGB() ====
 +Subscribes the Kniwwelinos RGB LED to specific MQTT topics. If a message is received, the LED color will be changed.
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string.
 +
 +The board will listen on //group/RGB/COLOR// for messages.
 +
 +**Message format:** 
 +
 +''"FF00FF", first 2 digits specify the RED, second the GREEN, third the BLUE component.''
 +
 +
 +
 +==== void MQTTconnectMATRIX() ====
 +Subscribes the Kniwwelinos MATRIX to specific MQTT topics. 
 +
 +if an MQTT group is set, the topic is automatically preceded with this group string. 
 +
 +The board will listen on //group/MATRIX/ICON// for icons. If a message is received, the ICON will be displayed.
 +
 +**Message format:**
 +
 +''"B1111100000111110000011111" 25 pixels binary one after the other, prefix B or\\
 +"0x7008E828A0" one byte for each 5px row, prefix 0x''
 +
 +The board will listen on //group/MATRIX/TEXT// for icons. If a message is received, the Text will be displayed.
 +
 +**Message format:** 
 +
 +''"Hello World!"''
 +
 +
 +
 +===== Wiring =====
 +
 +===== Examples =====
 +