基于MCU微控制器的智能穿戴設(shè)備設(shè)計思路

國際即時新聞（原文：英文）

Wearable Technology Is Changing Lives

The wrist is in great demand, as are many other parts of the body. Even the clothes we wear are becoming part of the next big thing; technology is going (even more) mobile as the concept of wearable technology takes hold. As an emerging sector, it is dependent on a number of technologies but none more so than integrated electronics. Fortunately for developers, embedded electronics is arguably also the most mature aspect of wearable technology, and as such offers many opportunities for OEMs to help shape this new phenomenon. Wearable technology is expected to include electronics, fabrics, biologics, biochemicals and renewable energy in a way that has never been seen before. It provides an opportunity for immeasurable innovation in a market that will likely be in a state of flux for many decades, as it augments and merges with other aspects of modern life. We are already taking the first tentative steps on a journey that could change modern life forever.?Key attributes?The humble fob watch appeared during the 16th century and remained largely unchanged until the First World War, when it was moved to the wrist predominantly for convenience. This could be considered the first ever example of ‘wearable technology’ and it has endured for an entire century as, fundamentally, a method for keeping time. Of course, since the introduction of integrated electronics the functionality of the watch has changed immensely and so it is logical that it would be the target for some of the first modern examples of wearable devices. Market analyst IHS Electronics & Media defines this class of device as being worn for extended periods of time, with the user experience being significantly enhanced as a result, while having advanced circuitry, wireless connectivity and independent processing capability. It further defines the categories for wearable technology as being: Fitness and Wellness; Healthcare and Medical; Industrial; Military; and Infotainment. Predominantly, these five categories comprise various forms of the acquisition, processing and displaying of data, which reiterates the need for local processing capability. Of course, at a more technical level, other key attributes of any device intended to be worn for extended periods during various levels of activity will be size and power; in both cases, the smaller the better. These are requirements that Integrated Device Manufacturers have observed for many years, furthered by Moore’s Law and developments in fabrication and packaging technologies. The challenge now is to combine advanced semiconductor technology with emerging ‘smart’ solutions in fabrics, sensors and energy. Every aspect of wearable technology will rely on the combination of the most optimal point-solutions; luckily there are already a number of microcontrollers available in volumes that effectively target this exciting new sector.?Leading solutions?Following the introduction of the Cortex-M0+ core by ARM with lead-partner Freescale Semiconductor, a number of IDMs have adopted the core for their ultra-low-power product offerings. The Cortex-M0+ offers a combination of features and low-power operation that perfectly matches a number of applications, and when delivered in the latest space-saving packages it represents a capable solution for wearable technology. The Kinetis KL02 from Freescale Semiconductor, for example, is available in a 20-pin WLCSP (wafer level, chip-scale packaging) option that measures less than 2 mm on each side and less than 0.6 mm high. Apart from being the smallest ARM-powered MCU available in volume, the KL02 features nine low-power modes and every device has a unique 80-bit identification number. Unique features help differentiate devices based on a common processor core such as the Cortex-M0+; illustrating this point, the LPC81XM family from NXP Semiconductor features a Pin Interrupt/Pattern Match Engine (Figure 1) that allows levels present on defined I/O to be assessed using predefined Boolean expressions to generate an interrupt. This could be useful in applications where the processor is required to spend extended periods in a deep-sleep mode, in order to preserve battery power.?

Figure 1: NXP’s LPC81 family features the Pattern Match Engine to reduce CPU activity.??The Zero Gecko family from Silicon Labs integrates a similar but more sophisticated feature with its Peripheral Reflex System; peripherals are able to communicate with each other while the core remains in a low-power sleep mode. The Gecko devices also employ Low Energy Sensor Interface (LESENSE) technology developed to allow the devices to control up to sixteen analog sensors without CPU intervention (Figure 2). It works in the 900 nA deep-sleep mode and can interface to capacitive, inductive and resistive sensors. This could be particularly relevant in wearable technology developed for health monitoring or home care, where sensors will be used to monitor physical conditions over long periods of time.?

Figure 2: The LESENSE interface in the Gecko Devices from Silicon Labs enable peripherals to interact with analogue peripherals without using the CPU.??As an emerging market, the word ‘typical’ can’t be applied to any wearable technology, however, as it is predominantly intended to be active only when worn, it would be reasonable to expect any device to spend a significant amount of time inactive. However, as any user will appreciate, when a device is needed it is always needed ‘immediately’, so time spent recharging depleted batteries is never welcome. For this reason, ultra-low-power modes will be crucial to ensure the device is always ready to go, and while the Cortex-M0+ core is designed to be low power, it is often down to the IDMs using it to implement the overall low-power strategy. To this end, the STM32L0 series from STMicroelectronics provides a Standby mode that consumes just 0.27 μA when the Real Time Clock is switched off (if the RTC remains on, the power rises to 0.65 μA at 1.8 V). The device takes just 60 μS to wake from Standby mode, although only data held in the Standby registers is retained. Although only offering two low-power modes, the Cortex-M0+-based ATSAMD20 family from Atmel also implements an intelligent peripheral approach to minimize core activity. The Event System allows peripherals to directly send and receive signals (events) that can be acted upon without waking the core. It operates in both asynchronous and synchronous modes and the Event System provides eight configurable channels comprising up to fifty-nine event ‘generators’ and fourteen event ‘users’ (Figure 3)

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Figure 3: Atmel’s Event System technology allows the ATSAMD20 to maintain low-power operation.??Energy harvesting?One element of wearable technology that has yet to be comprehensively addressed is providing the (admittedly small) energy the devices will require. Batteries remain the primary solution, but they are relatively large, so it will inevitably become necessary or desirable to power smaller devices with sustainable sources. Here, the concept of energy harvesting is gaining ground rapidly. Wearable technology is evolving quickly and analysts predict rapid growth with huge potential for innovation. As a result, it is likely to change the way we live forever.?

[譯]可穿戴技術(shù)改變生活

手腕的需求量很大，因為是身體的其他許多地方。即使我們穿正成為下一個大的事情的一部分衣服;技術(shù)是怎么回事（甚至更多）作為移動可穿戴技術(shù)的概念扎根。作為一個新興的行業(yè)，它依賴于一些技術(shù)，但莫過于集成電子元件。幸運的是開發(fā)商，嵌入式電子可以說是也可穿戴技術(shù)最成熟的方面，因此提供了許多機會為原始設(shè)備制造商，以幫助形成這種新現(xiàn)象?？纱┐骷夹g(shù)預(yù)計將包括電子產(chǎn)品，紡織品，生物，生物化學(xué)品和可再生能源在以前從來沒有見過的方式。它提供了不可估量的創(chuàng)新在市場上的機會，很可能會處于不穩(wěn)定狀態(tài)，幾十年來，因為它增強和融合了現(xiàn)代生活的其他方面。我們已經(jīng)采取的旅程，可能永遠(yuǎn)改變現(xiàn)代生活的第一個試探性步驟。關(guān)鍵屬性不起眼的FOB手表出現(xiàn)在16世紀(jì)和基本保持不變，直到第一次世界大戰(zhàn)，當(dāng)時它被轉(zhuǎn)移到手腕主要是為了方便。這可以被認(rèn)為是“可穿戴技術(shù)”有史以來第一次的例子，它已經(jīng)持續(xù)了整個世紀(jì)，從根本上，為保持時間的方法。

? ? ? ?當(dāng)然，自推出集成電子手表的功能發(fā)生了變化巨大，所以它是合乎邏輯的，這將是目標(biāo)的一些可穿戴設(shè)備的第一個現(xiàn)代的例子。市場分析員IHS與電子媒體這類裝置的定義為被磨損延長的時間周期，與用戶體驗被顯著增強，結(jié)果，雖然具有先進(jìn)的電路，無線連接和獨立處理能力。它進(jìn)一步定義了類別可穿戴技術(shù)作為是：健身與健康;醫(yī)療保健和醫(yī)療;工業(yè);軍事;和信息娛樂系統(tǒng)。主要是，這五大類包括各種形式的采集，處理和顯示數(shù)據(jù)，其中重申，需要對本地處理能力。當(dāng)然，在一個更技術(shù)層面上，也可以在各種級別的活動將尺寸和功率的佩戴長時間旨在任何設(shè)備的其他關(guān)鍵屬性;在這兩種情況下，越小越好。這些要求是集成設(shè)備制造商已經(jīng)觀察了很多年，摩爾定律的進(jìn)一步推動和發(fā)展制造和封裝技術(shù)?，F(xiàn)在的挑戰(zhàn)是，以先進(jìn)的半導(dǎo)體技術(shù)與新興的“智能”面料，傳感器和能源解決方案相結(jié)合?？纱┐骷夹g(shù)的各個方面將依靠最優(yōu)化的點解決方案的組合;幸運的是，已經(jīng)有一些在卷可微控制器，有效地瞄準(zhǔn)這一令人興奮的新部門。

? ? ? ? 領(lǐng)先的解決方案繼推出了Cortex-M0 +內(nèi)核的ARM所用鉛的合作伙伴飛思卡爾半導(dǎo)體，許多IDM廠商都采用了核心的超低功耗的產(chǎn)品供應(yīng)。在Cortex-M0 +提供的功能和低功耗運行的組合，完美匹配的一些應(yīng)用程序，而當(dāng)在最新的節(jié)省空間的封裝交付它代表著可穿戴技術(shù)有能力的解決方案。該的Kinetis KL02飛思卡爾半導(dǎo)體，例如，在一個20引腳WLCSP（晶圓級芯片尺寸封裝）選項測量小于2毫米，每邊和小于0.6毫米高可用。除了是最小的ARM供電MCU批量上市，該KL02具有9個低功耗模式，每個設(shè)備都有一個唯一的80位識別碼。獨特的功能，幫助區(qū)分基于一個共同的處理器核心設(shè)備，如在Cortex-M0 +;說明這一點上，LPC81XM家人從恩智浦半導(dǎo)體公司有引腳中斷/模式匹配引擎（圖1），使本上定義的I / O使用預(yù)定義的布爾表達(dá)式產(chǎn)生一個中斷評估水平。這可能是在其中處理器需要花費長時間處于深睡眠模式，以節(jié)省電池電量的應(yīng)用是有用的。

恩智浦LPC81系列圖1圖：恩智浦的LPC81系列采用模式匹配引擎，以減少CPU活動。零壁虎家族Silicon Labs的集成與周邊反射系統(tǒng)類似但更復(fù)雜的功能;外設(shè)能夠與彼此通信，而核心保持在低功率休眠模式。

壁虎器件還采用了開發(fā)，使設(shè)備控制多達(dá)十六個模擬傳感器而無需CPU干預(yù)（圖2）低能量傳感器接口（LESENSE）技術(shù)。它工作在900 nA的深度睡眠模式，可以連接到電容，電感和電阻傳感器。這可能是在對健康監(jiān)測或家庭護理，其中，傳感器將被用于監(jiān)控在很長一段時間的物理條件開發(fā)的可佩戴的技術(shù)特別相關(guān)。

從Silicon Labs的圖2中的壁虎設(shè)備LESENSE界面的圖片：從Silicon Labs公司的壁虎設(shè)備LESENSE接口使外設(shè)與模擬外設(shè)交互，而無需使用CPU。作為一個新興市場，單詞“典型”不能然而，適用于任何可穿戴的技術(shù)，因為它是主要打算成為活性只有當(dāng)穿戴時，這將是合理預(yù)期的任何設(shè)備花費顯著量的時間不活動。然而，正如任何用戶會明白，當(dāng)需要一個設(shè)備，它總是需要“立即”，所以花費的時間充電耗盡的電池是不歡迎。出于這個原因，超低功耗模式將是至關(guān)重要的，以確保設(shè)備隨時準(zhǔn)備去，而在Cortex-M0 +內(nèi)核的設(shè)計是低功耗，它往往是下跌的IDM廠商使用它來實現(xiàn)整體低功耗的策略。

? ? ?為此，該STM32L0系列意法半導(dǎo)體提供了待機模式，當(dāng)實時時鐘被關(guān)閉，消耗只是0.27μA（如果RTC持續(xù)工作，電源上升到0.65μA在1.8 V）。該設(shè)備僅需60微秒從待機模式喚醒，雖然只在待機寄存器中的數(shù)據(jù)將被保留。雖然只提供了兩個低功耗模式中，Cortex-M0 +的ATSAMD20家人從Atmel還實現(xiàn)了智能外設(shè)的方法，以減少核心活動。該事件系統(tǒng)可以讓外設(shè)直接發(fā)送和接收信號（事件），可以依據(jù)執(zhí)行不驚醒的核心。它工作在異步和同步模式和事件系統(tǒng)提供了包括多達(dá)59事件'發(fā)電機'十四事件“用戶”（圖3）八個可配置的通道。

Atmel的事件系統(tǒng)技術(shù)圖3的圖像：Atmel的事件系統(tǒng)技術(shù)允許ATSAMD20保持低功耗運行。能量收集要全面解決可穿戴技術(shù)的內(nèi)容之一，目前尚未是提供（誠然小）能源設(shè)備將需要。電池仍是主要的解決方案，但它們是比較大的，所以它必然成為必要的或希望與動力源的可持續(xù)小型設(shè)備。在這里，能量采集的概念迅速抬頭?？纱┐骷夹g(shù)正在發(fā)展迅速，分析師預(yù)測有巨大的創(chuàng)新潛力快速增長。因此，它很可能會改變我們的生活永遠(yuǎn)的方式。