Epson S1D13705 technical manual Default SwivelView Mode

Epson Research and Development	Page 77
Vancouver Design Center

12 SwivelView™

Many of todays applications use the LCD panel in a portrait orientation. In this case it becomes necessary to “rotate” the displayed image by 90°. This rotation can be done by software at the expense of performance or, it can be done by the S1D13705 hardware with no CPU penalty.

There are two SwivelView modes: Default SwivelView Mode and Alternate SwivelView Mode.

12.1 Default SwivelView Mode

Default SwivelView Mode requires the SwivelView image width be a power of two, e.g. a 240-line panel requires a minimum virtual image width of 256. This mode should be used whenever the required virtual image can be contained within the integrated display buffer (i.e. virtual image size ≤ 80K bytes), as it consumes less power than the Alternate SwivelView Mode.

For example, the panel size is 320x240 and the display mode is 8 bit-per-pixel. The virtual image size is 320x256 which can be contained within the 80K Byte display buffer.

Default SwivelView Mode also requires Memory Clock (MCLK) ≥ Pixel Clock (PCLK).

The following figure shows how the programmer sees a 240x320 image and how the image is displayed. The application image is written to the S1D13705 in the following sense: A–B–C–D. The display is refreshed by the S1D13705 in the following sense: B-D-A-C.

physical memory start address

320

256

A B E

SwivelView window

C D

240

image seen by programmer = image in display buffer

	E
display	B		SwivelView window	D	240
	A			C
start
address
		320
	image refreshed by S1D13705

256

Figure 12-1: Relationship Between The Screen Image and the Image Refreshed by S1D13705 in Default Mode

Hardware Functional Specification	S1D13705
Issue Date: 02/02/01	X27A-A-001-10