無線傳感器設(shè)計(jì)中功耗與性能的平衡

　　無論是電池供電，甚至能源消耗，無線傳感器設(shè)計(jì)需要仔細(xì)權(quán)衡電力需求和運(yùn)營能力，以達(dá)到性能目標(biāo)。對于工程師來說，轉(zhuǎn)化為精心挑選的MCUs和收發(fā)器能夠滿足嚴(yán)格的功率預(yù)算，可以在范圍和靈敏度不同無線網(wǎng)絡(luò)提供傳感器數(shù)據(jù)。本文將展示如何將這些設(shè)計(jì)目標(biāo)，可以滿足使用一系列的MCU，收發(fā)器和集成解決方案供應(yīng)商如AMS、EnOcean、集成、芯片技術(shù)，Silicon Labs、德克薩斯文書。

　　在其最基本的形式，一個(gè)無線傳感器包括主機(jī)單片機(jī)和無線收發(fā)，以及電源系統(tǒng)和一個(gè)模擬前端（AFE）不同的復(fù)雜性取決于應(yīng)用（圖1）。對于設(shè)計(jì)師來說，既擴(kuò)展范圍和無線傳感器的設(shè)計(jì)最大功率效率要求的超低功耗MCU和收音機(jī)仔細(xì)選擇。

　　Figure 1： In a wireless sensor， the MCU and transceiver are key components in determining power and communications performance. （Courtesy of Texas Instruments.）

　　Although active power consumption specifications quoted in datasheets may be sufficient in some cases， selection typically requires a broader look at device performance characteristics associated with the device‘s available low-power operating modes. For example， an MCU that specs out with slightly higher active power requirements than another might still provide superior overall power savings if it offers different options for low-power modes and if it includes features and characteristics that ensure maximum time spent in its lowest power modes.

　　That notion of heightened efficiency fuels a trend toward use of 16- and even 32-bit MCUs in applications long considered the sole domain of 8-bit MCUs. With their wider data paths， 16- and 32-bit MCUs offer greater code density that in many cases allows for more efficient code execution – translating to faster completion of tasks and a quicker return to low-power sleep modes.