開發(fā)工具調(diào)整功耗的微控制器

　　一方面將許多設(shè)備組成了物聯(lián)網(wǎng)，對低能耗的要求。解決這一需求需要在多層次的整體戰(zhàn)略的優(yōu)化。一個成功的設(shè)計需要的不僅僅是選擇低功耗元件，而且還使用軟件勉強可用的電池容量由這些組件，以最有效的方式一起工作。即使細微的變化，硬件和軟件的實施可以使整體能源使用的巨大差異。

　　大多數(shù)物聯(lián)網(wǎng)設(shè)備的核心是一個微控制器（MCU）設(shè)計的高能效。一個典型的低能量MCU包括一個智能外設(shè)陣列控制的I / O和必要的系統(tǒng)功能的核心處理器。串行端口（UART）通常能夠自動發(fā)送和接收數(shù)據(jù)，而在處理器內(nèi)核上運行的軟件只需要從適當(dāng)?shù)木彌_區(qū)傳輸字節(jié)，一旦數(shù)據(jù)接收完成。與鏈接的DMA傳輸可用的設(shè)備如從Silicon Labs EFM32系列MCU的壁虎，甚至相互作用可以被最小化。在這種情況下，處理器核心只需要喚醒檢查內(nèi)存的內(nèi)容，一旦整個消息已收到。

　　By allowing peripherals to manage I/O， the MCU can spend much of its time in sleep mode， where many parts of the MCU will be shut down and not draw power. Duty cycle is the ratio of time spent in active mode vs time spent asleep. A low duty cycle is important to battery powered IoT applications since sleep modes draw mere microamps， while active mode typically draws several orders of magnitude more.

　　A low duty cycle allows the processor core to sleep for a majority of the time， waking only to collect data or to communicate when necessary. The key to implementing a low duty cycle strategy is understanding how the software interacts with the hardware. Functions that cause the MCU to be awake too long need to be identified and then replaced or rewritten if possible. Traditionally， this has been difficult to achieve early in the development phase because such identification relies on finished hardware for testing.

　　The Pearl Gecko starter kit and similar evaluation boards from Silicon Labs include an Advanced Energy Monitor （AEM） function. When used in combination with the advanced tools in the company’s Simplicity Studio， it provides valuable insight into how much energy an application requires during the software development cycle. The information not only shows the effectiveness of sleep modes， but also function-level optimizations.