一個基於MQTT協定隨插隨用IoT平台之設計與實作

Abstract

近年來嵌入式系統隨著IC設計與技術不斷的進步，各式各樣的嵌入式開發板不斷的推出，功能也越來越強大以及價格也愈趨大眾化。加上無線網路技術之快速進展與普及，物聯網因此得到了很大的發展動力。物聯網中各種感應器需要依靠嵌入式開發板來讀取數據和傳送。然而不同廠商推出的嵌入式開發板提供的規格和硬體配置也會不一樣。因此，我們設計了一個隨插隨用的系統，此系統擁有一個統一的界面來讀取這些感應器。此外，此系統可以自動化的偵測和讀取感應器，使用者只需要插入感應器便可隨插隨用，不必介入感應器與嵌入式開發板的設定。這些得到的數據便可使用任何的嵌入式開發板透過網路傳送出去。 在傳送數據方面，我們使用了一個在網路應用層中一個輕量化的協定，名為MQTT Protocol。此協定使用的封包比較小，這樣可以降低延遲及電量消耗。好處是可以增加嵌入式開發板的傳送能力以及持續使用時間。另外， MQTT Protocol使用發佈(Publish)/訂閱(Subscribe)訊息模式。我們設計了一個階層式訊息的命名方式，以針對來自不同的嵌入式開發板以及對統一的隨插隨用的系統做後續有效的處理。

In recent years, with the advance of IC design and manufacturing technology, the usage of embedded systems has boosted up. There are many different brands of embedded system boards. The functions of nowadays embedded boards are much powerful and the cost are affordable. As a consequence, Internet of Things (IoT) has achieved a very quick development. IoT sensors required embedded board to read the data which is then sent to Internet or cloud servers. However, the hardware configuration by different manufacturers of embedded boards are different, hence it is hard to setup a one-fit-all IoT platform. In this thesis, we tried to develope a plug and play system with a generic interface to automatically detect and read the sensors. A user only needs to connect the sensors to the plug and play system to run the application. Without human configuration, the data of the sensor can be read, and then the data can be published to the Internet via any kinds of embedded boards. For data transport, we used a lightweight protocol in application layer of Internet. The packet size of this protocol is much smaller and it can reduce the latency and power consumption. Therefore, we can increase the transmission throughput and the utilization of embedded boards. MQTT protocol is using Publish/Subscribe Topic based mechanism. We designed a hierarchical topic name to handle the data from different embedded boards and the plug and play system.