利用單片機LCD節省電力

　　現在，微控制器（MCU）作為許多低能量和便攜式系統的核心，但壓力不斷地在延長電池壽命的同時實現更廣泛的功能。維持長電池壽命的一個好方法是在絕對必要時只運行處理器，但這可能使系統更難使用，因為這可能意味著將用戶接口組件（如顯示器）斷電。然而，有越來越多的MCU，可以選擇性地關閉處理器的同時保持LCD圖像。

　　例如，水表在內置LCD上不斷顯示讀數是很有用的。然而，為了保持MCU系統的有效性，米的電池可能是浪費的，以防用戶在白天某個時候查看它。通過無需處理器核心的直接干預就能驅動LCD，因此有可能選擇性地降低MCU的部分，同時保持lcd的存儲圖像。

　　Figure 1： Many low-energy embedded systems now incorporate an LCD-based user interface. （Source： Energy Micro）

　　Broadly speaking， the power consumption of any active CMOS electronic circuit is given by the formula CV2f. In this formula， C is the total capacitance of the circuitry within the device that needs to be charged and discharged during a cycle. V is the power supply voltage and f is the frequency at which the device runs. As a result， one factor that leads to reductions in power consumption is the supply voltage – the quadratic relationship between voltage and energy provides dramatic savings.

　　Another saving comes from reducing the frequency of operation although this may only have an impact on power rather than energy. If it takes the same number of cycles to run an algorithm but they are spread over a longer period of time， overall energy consumption can increase. This is due to the leakage component1。