AREA EFFICIENT, LOW POWER LCD CONTROLLER WITH EXTERNAL BITMAPPED CURSOR
Original Publication Date: 1997-Dec-01
Included in the Prior Art Database: 2002-Jun-14
Liquid Crystal Display (LCD) controllers in pager applications typically have simple cursor display such as a block shape with blink capability. Display of complex graphic cursor is typically done in software which requires a lot of power and time. As such, traditional pagers cursor display have limited shapes and features in order to save power. This article describes a method in which complex cursor shapes can be displayed using hardware with minimal area cost and power consumption Traditionally, Liquid Crystal Display (LCD) Controllers display complex graphic cursors via software; since the available hardware cursor on them is very simple. Software implementation is obviously expensive, in terms of power and time, since every time the cursor is moved, the entire external screen display memory has to be updated. The low power LCD Controller implements a bitmapped cursor in hardware, thus reducing the power consumption and software time overhead. At the same time the effective area-increase is mini- mized by storing the cursor bitmap in external memory instead of having internal registers and utilizing the Direct Memory Access (DMA) sub- module already existing on the LCD controller. The DMA transfers cursor data from external memory to an internal register only when cursor data is required, as determined by the internal logic thus minimizing power and area. The Low Power LCD Controller is thus an excellent candidate for modem graphic-oriented, low-power, area-efftcient micro- controllers.