sed1355 ETC-unknow, sed1355 Datasheet - Page 184

• Manufacturer Part Number: sed1355
• Description: Sed1355 Embedded Ramdac Lcd/crt Controller
• Manufacturer: ETC-unknow

Page 28
5.3 Split Screen
SED1355
X23A-G-003-05
Example 5: Scroll down one line for a 16 color 640x480 virtual image using a 320x240 single
1.
2.
3.
Occasionally the need arises to display two distinct images on the display. For example, we may
write a game where the main play area will rapidly update and we want a status display at the bottom
of the screen.
The Split Screen feature of the SED1355 allows a programmer to setup a display for such an appli-
cation. The figure below illustrates setting a 320x240 panel to have Image 1 displaying from scan
line 0 to scan line 99 and image 2 displaying from scan line 100 to scan line 239. Although this
example picks specific values, image 1 and image 2 can be shown as varying portions of the screen
To scroll down we need to know how many words each line takes up. At 16 colors (4 bpp)
each byte contains two pixels so each word contains 4 pixels.
offset_words = pixels_per_line / pixels_per_word = 640 / 4 = 160 = A0h
We now know how much to add to the start address to scroll down one line.
Increment the start address by the number of words per virtual line.
start_address = start_address + words
Separate the start address value into three bytes. Write the LSB to register [10h] and the MSB
to register [12h].
Figure 5-5: 320x240 Single Panel For Split Screen
panel LCD.
Screen 1 Display Line Count Register = 99 lines
Scan Line 100
Scan Line 239
Scan Line 99
Scan Line 0
...
...
.
Image 1
Image 2
Epson Research and Development
Programming Notes and Examples
Vancouver Design Center
Issue Date: 99/04/27