SED1374 Datasheet, PDF (87/420 Pages) Epson Company – SED1374 Embedded Memory Color LCD Controller

Epson Research and Development
Vancouver Design Center
Page 79
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. This rotation can be done by software
at the expense of performance or, as with the SED1374, it can be done by hardware with
no CPU penalty.
There are two SwivelView modes: Default SwivelView and Alternate SwivelView.
12.1 Default SwivelView Mode
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 ≤ 40k bytes), as it consumes less power than the Alternate
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) ≥ 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 SED1374 in the following sense:
A–B–C–D. The display is refreshed by the SED1374 in the following sense: B-D-A-C.
physical
memory
start
address
256
A
B
E
SwivelView
window
display
start
address
C
D
240
image seen by programmer
= image in display buffer
320
image refreshed by SED1374
Figure 12-1: Relationship Between The Screen Image and the Image Refreshed by SED1374
Hardware Functional Specification
Issue Date: 99/04/29
SED1374
X26A-A-001-02