ssd1908 Solomon Systech Limited:, ssd1908 Datasheet - Page 143

• Manufacturer Part Number: ssd1908
• Description: Lcd Drivers,lcd Controllers
• Manufacturer: Solomon Systech Limited:

19.3 270° Display Rotate Mode
19.3.1 Register Programming
SSD1908
Figure 19-3 : Relationship Between The Screen Image and the Image Refreshed in 270 ° ° ° ° Display Rotate
Line Address Offset
The following figure shows how the programmer sees a 320x480 rotated image and how the image is
being displayed. The application image is written to the SSD1908 in the following sense: A–B–C–D. The
display is refreshed by the SSD1908 in the following sense: C-A-D-B.
Enable 270 ° ° ° ° Display Rotate Mode
Display Start Address
physical memory
start address
The Main Window Line Address Offset register (REG[78h], REG[79h]) is based on the display
width and programmed using the following formula.
Set Display Rotate Mode Select bits to 11 (REG[71h] bits 1:0 = 11).
The display refresh circuitry starts at pixel “C”, therefore the Main Window Display Start Address
registers (REG[74h], REG[75h], REG[76h]) must be programmed with the address of pixel “C”.
To calculate the value of the address of pixel “C” use the following formula (assumes 8bpp color
depth).
Rev 1.0
Main Window Line Address Offset bits 9-0
= Display width in pixels ÷ (32 ÷ bpp)
= 480 pixels ÷ (32 ÷ 8 bpp)
= 120 (78h)
Main Window Display Start Address bits 16-0
= (Image address + ((panel width – 1) x image width x bpp ÷ 8) ÷ 4)
= (0 + ((480 pixels – 1) x 320 pixels x 8 bpp ÷ 8) ÷ 4)
= 38320 (95B0h)
P 133/133
image seen by programmer
= image in display buffer
A
C
Window
Display
Rotate
320
Oct 2003
B
D
display start address
(panel origin)
Mode.
image refreshed by SSD1908
480
Solomon Systech