Epson S1D13705 technical manual Introduction To Hardware Rotation, Default Portrait Mode

Epson Research and Development	Page 37
Vancouver Design Center

7 Hardware Rotation

7.1 Introduction To Hardware Rotation

Many of todays applications use the LCD panel in a portrait orientation (typically LCD panels are landscape oriented). In this case it becomes necessary to “rotate” the displayed image. This rotation can be done by software at the expense of performance or, as with the S1D13705, it can be done by hardware with no performance penalty.

This discussion of display rotation is intended to augment the excellent description of the hardware functionality found in the Hardware Functional Specification.

The S1D13705 supports two portrait modes: Default Portrait Mode and Alternate Portrait Mode.

7.2 Default Portrait Mode

Default portrait mode was designed to reduce power consumption for portrait mode use. The reduced power consumption comes with certain trade offs.

The most obvious difference between the two modes is that Default Portrait Mode requires the portrait width be a power of two, e.g. a 240-line panel, used in portrait mode, requires setting a virtual width of 256 pixels. Also default portrait mode is only capable of scrolling the display in two line increments.

The benefits to using default portrait mode lies in the ability to use a slower input clock and in reduced power consumption.

The following figure depicts the ways to envision memory layouts for the S1D13705 in default portrait mode. This example uses a 320x240 panel.

Programming Notes and Examples	S1D13705
Issue Date: 02/01/22	X27A-G-002-03