1 | # Arduino Client for MQTT
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2 |
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3 | This library provides a client for doing simple publish/subscribe messaging with
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4 | a server that supports MQTT.
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5 |
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6 | ## Examples
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7 |
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8 | The library comes with a number of example sketches. See File > Examples > PubSubClient
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9 | within the Arduino application.
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10 |
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11 | Full API documentation is available here: http://pubsubclient.knolleary.net
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12 |
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13 | ## Limitations
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14 |
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15 | - It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
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16 | - The maximum message size, including header, is **128 bytes** by default. This
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17 | is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h`.
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18 | - The keepalive interval is set to 15 seconds by default. This is configurable
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19 | via `MQTT_KEEPALIVE` in `PubSubClient.h`.
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20 | - The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by
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21 | changing value of `MQTT_VERSION` in `PubSubClient.h`.
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22 |
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23 |
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24 | ## Compatible Hardware
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25 |
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26 | The library uses the Arduino Ethernet Client api for interacting with the
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27 | underlying network hardware. This means it Just Works with a growing number of
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28 | boards and shields, including:
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29 |
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30 | - Arduino Ethernet
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31 | - Arduino Ethernet Shield
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32 | - Arduino YUN â use the included `YunClient` in place of `EthernetClient`, and
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33 | be sure to do a `Bridge.begin()` first
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34 | - Arduino WiFi Shield - if you want to send packets > 90 bytes with this shield,
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35 | enable the `MQTT_MAX_TRANSFER_SIZE` define in `PubSubClient.h`.
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36 | - Sparkfun WiFly Shield â [library](https://github.com/dpslwk/WiFly)
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37 | - TI CC3000 WiFi - [library](https://github.com/sparkfun/SFE_CC3000_Library)
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38 | - Intel Galileo/Edison
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39 | - ESP8266
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40 |
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41 | The library cannot currently be used with hardware based on the ENC28J60 chip â
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42 | such as the Nanode or the Nuelectronics Ethernet Shield. For those, there is an
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43 | [alternative library](https://github.com/njh/NanodeMQTT) available.
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44 |
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45 | ## License
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46 |
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47 | This code is released under the MIT License.
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