S1D13704 Epson Electronics America, Inc., S1D13704 Datasheet - Page 86

• Manufacturer Part Number: S1D13704
• Description: LCD Controller
• Manufacturer: Epson Electronics America, Inc.

Page 80
12 SwivelView™
12.1 Default SwivelView Mode
S1D13704
X26A-A-001-06
physical
memory
address
start
Figure 12-1: Relationship Between The Screen Image and the Image Refreshed by S1D13704
image seen by programmer
= image in display buffer
C
A
SwivelView
window
Many of todays applications use the LCD panel in a portrait orientation. 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 S1D13704, it can be done by hardware with
no CPU penalty.
There are two SwivelView modes: Default SwivelView and Alternate SwivelView.
Default SwivelView Mode requires the portrait 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
SwivelView mode.
For example, the panel size is 320x240 and the display mode is 4 bit-per-pixel. The virtual
image size is 320x256 which can be contained within the 40k Byte display buffer.
Default SwivelView Mode also requires memory clock (MCLK)
The following figure shows how the programmer sees a 240x320 image and how the image
is displayed. The application image is written to the S1D13704 in the following sense:
A–B–C–D. The display is refreshed by the S1D13704 in the following sense: B-D-A-C.
240
256
D
B
E
40k bytes), as it consumes less power than the Alternate
display
address
start
image refreshed by S1D13704
320
Epson Research and Development
Hardware Functional Specification
pixel clock (PCLK).
Vancouver Design Center
Issue Date: 02/02/01