Epson S1D13706 - Figure 12-1: Relationship between the Screen Image and the Image Refreshed in 90° Swivelview; Concept

Page 138
Epson Research and Development
Vancouver Design Center
S1D13706 Hardware Functional Specification
X31B-A-001-08 Issue Date: 01/11/13
12 SwivelView™
12.1 Concept
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.
12.2 90° SwivelView™
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.
Figure 12-1: Relationship Between The Screen Image and the Image Refreshed in 90
°
SwivelView.
image seen by programmer
= image in display buffer
480
SwivelView
window
480
320
AB
C
D
D
C
B
A
320
SwivelView
window
display start address
image refreshed by S1D13706
(panel origin)
physical memory
start address