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MQTT is a machine-to-machine (M2M)/"Internet of Things" (IOT) connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport. With an Arduino-compatible wireless soc, e.g. Realtek Ameba1 (RTL8195/RTL8710) dev. Board, we can create a MQTT client that sends our sensor data to the cloud or any other MQTT clients. The source code is available on github at, https://github.com/ambiot/amb1_arduino/blob/master/Arduino_package/hardware/libraries/MQTTClient/examples/mqtt_basic/mqtt_basic.ino The things that need to take note of, · The "mqttServer" refers to the MQTT-Broker, we use the MQTT sandbox "test.mosquitto.org", it is provided by IBM eclipse for developers to test MQTT. · "clientId" is an identifier for MQTT-Broker to identify the connected device. · "publishTopic" is the topic of the published message, we use "outTopic" in the example. The devices subscribe to "outTopic" will receive the message. · "publishPayload" is the content to be published. · "subscribeTopic" is to tell MQTT-broker which topic we want to subscribe to. Here we can use a chrome plugin "MQTTLens" to be a second MQTT client. You can find it in Chrome Web Store at, https://chrome.google.com/webstore/detail/mq-tt-lens-the-best/cgmogjdjpnemdlijokkdomfapcodiohh?utm_source=chrome-ntp-icon After setting up a “connection” and key in the same topics we used on Ameba, we should be able to see a “Hello World” message printed on the MQTT message console.
Temperature and humidity are 2 of the most important factors affecting people’s comfort level in an enclosed space. The DHT humidity and temperature sensor can read the ambient temperature and humidity every 2-3 seconds, and then pass the data to Ameba who will forward them to the server using MQTT protocol. Whoever “subscribing” to the right topic gets the data almost instantaneously. Users can then adjust the aircon mode or temperature according to the readings received. An android phone was used as an MQTT client and the Ameba RTL8195 Dev. Board acted as another MQTT client communicating with the android phone. Both clients have to connect to the same MQTT server before proceeding to the next step. The DHT sensor updates its data every 10 seconds to stay as accurate as possible. Once sensor data is received, Ameba then “publishes” the data to the MQTT server where all clients “subscribing” to the right topic gets the data displayed on the console. GitHub page https://github.com/Realtek-AmebaApp/Ameba_Examples/tree/master/RTL8195AM/003_DHT_MQTT Official pages https://www.amebaiot.com.cn/en/ https://www.amebaiot.com/en/ Facebook pages https://www.facebook.com/groups/AmebaIoT/ https://www.facebook.com/groups/AmebaIoTWW/ BiliBili channel https://space.bilibili.com/45777743
This is a simple IoT project based on the “mqtt basic” example that comes with the Arduino package when you install the RTL8195 on Arduino IDE. In this project, simple passive components are used to aid in demonstrating the power of bidirectional communication of MQTT protocol which is widely used in modern IoT applications for its advantages in speedy response and lightweight. In the video, an android tablet was used as a MQTT client and our Ameba RTL8195. Board acted as another MQTT client communicating with the android tablet. Both client have to connect to the same MQTT server before proceeding to the next step, you may choose to set up own MQTT server or using an online free server. Please refer to the video link, GitHub source code, https://github.com/Realtek-AmebaApp/Ameba_Examples/tree/master/RTL8195AM/002_MQTT_BASIC Official pages https://www.amebaiot.com.cn/en/ https://www.amebaiot.com/en/