Figure 12-1: Relationship Between The Screen Image And The Image Refreshed In 90° Swivelview; Concept - Epson S1D13706 Technical Manual

Page 138
12 SwivelView™

12.1 Concept

12.2 90° SwivelView™
physical memory
start address
A
SwivelView
C
image seen by programmer
= image in display buffer
Figure 12-1: Relationship Between The Screen Image and the Image Refreshed in 90° SwivelView.
S1D13706
X31B-A-001-08
Most computer displays are refreshed in landscape orientation – from left to right and top
to bottom. Computer images are stored in the same manner. SwivelView™ is designed to
rotate the displayed image on an LCD by 90°, 180°, or 270° in an counter-clockwise
direction. The rotation is done in hardware and is transparent to the user for all display
buffer reads and writes. By processing the rotation in hardware, SwivelView™ offers a
performance advantage over software rotation of the displayed image.
The image is not actually rotated in the display buffer since there is no address translation
during CPU read/write. The image is rotated during display refresh.
90° SwivelView™ requires the Memory Clock (MCLK) to be at least 1.25 times the
frequency of the Pixel Clock (PCLK), i.e. MCLK ≥ 1.25PCLK.
The following figure shows how the programmer sees a 320x480 portrait image and how
the image is being displayed. The application image is written to the S1D13706 in the
following sense: A–B–C–D. The display is refreshed by the S1D13706 in the following
sense: B-D-A-C.
B
window
display start address
(panel origin)
D
320
Epson Research and Development
Vancouver Design Center
480
image refreshed by S1D13706
Hardware Functional Specification
Issue Date: 01/11/13