用ZigBee綠色電源設計超低功耗無線自動化

　　新的協議和基準將促進從環境中獲取能量的超低功耗無線系統的發展。ZigBee聯盟提供的綠色電力規范允許使用低占空比的無線系統，并能從周圍獲得機械、熱能或太陽能。

　　一種新的ZigBee規范稱為綠色能源現在支持低成本的能源收集和超長的電池壽命為ZigBee無線應用的智能家居，而一個行業集團正在尋找基準超低功耗設備。

　　在ZigBee Pro 2012的綠色電源功能提供免費電池，能量收集設備的能力，加入任何綠色電源啟用ZigBee網絡。不需要電池，自給設備通常只收獲足夠的能量來傳送機械、熱能或射頻能量的簡短指令。例如，沒有電池的電燈開關會從開關上獲得能量。這種能量被捕獲，以向網絡發送“接通”或“關閉”命令，以接通或關閉適當的光，因此，自供電的電燈開關可以位于房間的任何地方，而無需運行電源線。

　　However， the discussion on the performance of devices now moves from the current and power consumption to the overall energy consumed by the system. At these low levels of microjoules， there is no standardized way to evaluate different systems， so new benchmarks are also being developed separately that will give engineers key information about the performance of the microcontrollers and wireless systems that are used in these home automation installations.

　　Adapting the ZigBee protocol is a lower power approach than using other approaches. A typical Wi-Fi card in a laptop PC uses roughly 2 kJ of energy in an hour （assuming a 200 mA， 3 V transceiver runs continuously）。 In comparison， a 30 W lamp on for an hour consumes 100 kJ， 50 times as much. The ZigBee set-top box remote control using the R4CE protocol uses just 20 mJ per hour， a factor of 100，000 times less than the Wi-Fi card.