51 lines
2.0 KiB
Markdown
51 lines
2.0 KiB
Markdown
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# Arduino Client for MQTT
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This library provides a client for doing simple publish/subscribe messaging with
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a server that supports MQTT.
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## Examples
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The library comes with a number of example sketches. See File > Examples > PubSubClient
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within the Arduino application.
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Full API documentation is available here: https://pubsubclient.knolleary.net
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## Limitations
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- It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
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- The maximum message size, including header, is **256 bytes** by default. This
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is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h` or can be changed
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by calling `PubSubClient::setBufferSize(size)`.
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- The keepalive interval is set to 15 seconds by default. This is configurable
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via `MQTT_KEEPALIVE` in `PubSubClient.h` or can be changed by calling
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`PubSubClient::setKeepAlive(keepAlive)`.
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- The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by
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changing value of `MQTT_VERSION` in `PubSubClient.h`.
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## Compatible Hardware
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The library uses the Arduino Ethernet Client api for interacting with the
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underlying network hardware. This means it Just Works with a growing number of
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boards and shields, including:
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- Arduino Ethernet
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- Arduino Ethernet Shield
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- Arduino YUN – use the included `YunClient` in place of `EthernetClient`, and
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be sure to do a `Bridge.begin()` first
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- Arduino WiFi Shield - if you want to send packets > 90 bytes with this shield,
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enable the `MQTT_MAX_TRANSFER_SIZE` define in `PubSubClient.h`.
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- Sparkfun WiFly Shield – [library](https://github.com/dpslwk/WiFly)
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- TI CC3000 WiFi - [library](https://github.com/sparkfun/SFE_CC3000_Library)
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- Intel Galileo/Edison
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- ESP8266
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- ESP32
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The library cannot currently be used with hardware based on the ENC28J60 chip –
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such as the Nanode or the Nuelectronics Ethernet Shield. For those, there is an
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[alternative library](https://github.com/njh/NanodeMQTT) available.
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## License
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This code is released under the MIT License.
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