Powering-Down Graphics

　　Powering-Down Graphics

　　今天的用户希望他们的移动设备有出色的图形功能，但仍然希望可以接受的电池寿命。显示器的其他用户也期望低功耗。这些标准显然拉在不同的方向，但有低功耗微控制器，如果正确应用，可以走很长的路来解决这些问题。本文将看看三个这样的设备，详细介绍了三个基于图形的应用程序。

　　第一个应用程序将用于驱动电子纸显示器从Silicon Labs的EFM32微控制器。然后，文章将看看两种不同的方式驱动LCD使用标准的微控制器。在这些第一，从Microchip的PIC32单片机为开发controllerless图形化嵌入式应用电路部分组成。第二，从意法半导体标准ST62单片机将用于驱动LCD。

　　Electronic paper display

　　The growth in e-readers has created a demand for displays that look as if they are made from paper， to create a more book-like experience for the reader. Such displays are reflective in that they rely purely on ambient light; there is no backlight. They are bistable in that they will retain an image even if the power is disconnected. As well as e-readers， they are also used in industrial signage， electronic shelf labels and other applications where the image is not updated frequently. When showing a static image， they draw no current and thus battery life is extended. However， they need a lot of current to update the image， which can take one to two seconds.

　　Transparent capsules filled with dark-colored oil make up the pixels. Within the oil are white， negatively charged titanium dioxide particles. There are electrodes on the front and back of the capsules. If the front electrode is positively charged， the particles are drawn toward it and the pixel appears white. If the back electrode is positively charged， the particle goes toward that leaving the black oil visible， so the pixel appears black. This is illustrated in Figure 1.