利用单片机LCD节省电力

　　利用单片机LCD节省电力

　　现在，微控制器（MCU）作为许多低能量和便携式系统的核心，但压力不断地在延长电池寿命的同时实现更广泛的功能。维持长电池寿命的一个好方法是在绝对必要时只运行处理器，但这可能使系统更难使用，因为这可能意味着将用户接口组件（如显示器）断电。然而，有越来越多的MCU，可以选择性地关闭处理器的同时保持LCD图像。

　　例如，水表在内置LCD上不断显示读数是很有用的。然而，为了保持MCU系统的有效性，米的电池可能是浪费的，以防用户在白天某个时候查看它。通过无需处理器核心的直接干预就能驱动LCD，因此有可能选择性地降低MCU的部分，同时保持lcd的存储图像。

　　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。