藍牙技術在嵌入式系統設計中的應用

　　提起藍牙，非工程師首先想到的是無線耳機，它似乎從幾乎所有智能手機用戶的耳朵中萌芽。另一方面，嵌入式設計師看到一種低成本、互操作的、電池友好的技術，可以使他們的產品與越來越多的消費者和工業設備交換數據文件和多媒體流（圖1）。在本文中，我們將探討成功集成該技術的一些設計問題，以及新一代專門為嵌入式應用設計的藍牙設備的體系結構和功能集。

　　Figure 1： Bluetooth， and its cousin Bluetooth low-power， provide an efficient， near-universal conduit for data between embedded applications such as glucometers （top）， blood pressure meters， or other health care equipment （bottom） and a standard smartphone or tablet computer.

　　Different profiles

　　The original Bluetooth specification1 and all of its variants operate in the in the globally unlicensed Industrial， Scientific， and Medical （ISM） 2.4 GHz short-range band using frequency-hopping spread-spectrum transmission. Nearly all devices on the market today support the Bluetooth v1.2 specification and its 720 kbit/s data rate. Even many low-cost products also support the V2.0/V2.1 +EDR specifications， which feature improved security， simpler pairing between devices， and modes which enable reduced power consumption. The recently-introduced Bluetooth low energy specification2 features dramatically-reduced power consumption at the cost of reduced data rates and shorter effective range.