标签: mode

This is not a trick question. Your options for answers are as follows: Always Sometimes Maybe It depends As with most engineering issues, the correct answer is either c or d, based on your perspective, your priorities, and the specifics of the situation. It also is related to the basic definition of power and energy: Energy is the time integral of power. Many people, however, confuse "energy" and "power" both in concept and as physical entities.   I started thinking about this again after reading a brief Wall Street Journal piece, " Europe's Dirty Floor Mandate " (subscription required), and a related article in the Telegraph, " EU to ban high-energy hair dryers, smartphones and kettles ." According to the WSJ, "Consumers are only now noticing Regulation 666/2013, adopted by the European Commission last year and taking effect next month, which bans the manufacture or importing of vacuum motors whose power output exceeds 1,600 watts, with the limit dropping to 900 watts after Sept. 1, 2017."   The Telegraph reports that similar power-reduction plans are in place for appliances such as hair dryers. All of this, of course, is in the name of "saving energy."   Here's the problem: If you can accomplish the same task with a lower-power motor as compared with a higher-power motor and in the same time , you certainly will have saved energy. But if it takes longer due to the reduced power level, you may end up using the same or even more energy. In the case of reducing the motor power in a vacuum cleaner, the consumer may have to run it longer, so we are back to basics: Actual energy used is the time integral of power.   Perhaps it is possible to reduce a vacuum cleaner's power consumption significantly, while getting the same results, by using a more efficient motor and airflow arrangement. I don't know how efficient a vacuum cleaner really is or how much upside potential there may be. I do know that more efficient motors generally require more copper wire in their windings, so power consumption may be reduced for a given suction rating and airflow volume, but the total cradle-to-grave energy "expense" may actually be higher. It's hard to say.   (Side note: I never understood why vacuum cleaner "powerfullness" was discussed in terms of motor current draw -- amps. That always seemed to be looking at the wrong end of the story, and it assumed all motors and their vacuum cleaners had equal input current/output performance ratios.)   What really has me puzzled is the push toward greater electrical efficiency in appliances where the core function is to provide heat, such as hair dryers. A 1,000W dryer will surely take longer to dry hair than a 1,500W unit.   Aren't hair dryers and other electric-heat products 100% efficient by definition, except perhaps for some losses in their fan and an IR drop in their AC wires? I once measured a commodity 1,200W hair dryer's power consumption in no-heat/cold-air-only mode. I found that the very noisy fan took only about 50 W, an insignificant amount compared to the 1,200W full-heat rating. Even a somewhat better fan motor would not make much difference in overall energy use.   Have you seen other examples where people confuse energy with power and think that, by reducing one, they will automatically save on the other? Have you seen cases where reducing power consumption has actually increased energy use? It even happens with power-miser low-power systems that have a sleep mode. Sometimes it is more energy efficient to have a short, high-power activity burst and a longer sleep period, rather than a longer, medium-power burst and shorter sleep mode.

 FTDI最新推出的FT311D是你们最好的选择。 FT311D 是一个可用在多介面的安卓主控IC, 能够提供即时由安卓USB埠(B)到GPIO, UART, PWM, I2C主控, SPI从或SPI主控介面。 可简易地通过电阻控制使用模式, 有了这个新的芯片，系统开发商可以加强这种现今流行而且庞大的移动通信市场的进行连接与创建适合用户的应用，充分利用安卓(Android)平台资源的能力，高性能的处理，加速度计，触摸屏接口等优势。 FT311D是利用Android Open Accessory mode (AOA)实现安卓外接设备应用, FT311D已经把API写好, 工程师可以直接呼叫函数. 只要在安卓装上APK, 就可实现安卓接GPIO, UART(串口), PWM, I2C主控, SPI从或SPI主控介面。

現在目前普遍工程師們在開發安卓週邊設備,遇到的問題是不能在安卓上安裝驅動, 對面是否需要root機的問題. 現在Google 推出的Open accessory mode(AOA), 是專門針對開發安卓週邊設備, 而FT311D就是為工程師提供了方便, FT311D可以實現安卓USB PORT B 接串口(UART), GPIO, PWM, I2C, SPI等介面, 而且API也已經寫好, 工程師只要呼叫函数就可以使用所選用的介面, 作讀寫傳輸