Powering-Down Graphics

　　今天的用戶希望他們的移動設備有出色的圖形功能，但仍然希望可以接受的電池壽命。顯示器的其他用戶也期望低功耗。這些標準顯然拉在不同的方向，但有低功耗微控制器，如果正確應用，可以走很長的路來解決這些問題。本文將看看三個這樣的設備，詳細介紹了三個基于圖形的應用程序。

　　第一個應用程序將用于驅動電子紙顯示器從Silicon Labs的EFM32微控制器。然后，文章將看看兩種不同的方式驅動LCD使用標準的微控制器。在這些第一，從Microchip的PIC32單片機為開發(fā)controllerless圖形化嵌入式應用電路部分組成。第二，從意法半導體標準ST62單片機將用于驅動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.