Epson SED1352 Technical Manual page 136

Page 40
5.4.4.1 Displaying a Single Image on a Dual Panel
The following is the procedure to show a single image on a dual panel LCD. In this procedure the single image is broken
into two smaller images; image 1 is placed on the top panel and image 2 is placed on the bottom panel. For this example
the SDU1352B0x is used with a 4 gray shade 640x480 dual panel LCD; the Memory Interface is set to 16 bits, and 128k
of display memory is available.
1. Determine whether the Display Start Address Registers refer to bytes or words.
Since the Memory Interface is set to 16 bits, the Display Start Address Registers refer to words. Note that when ad-
dresses refer to words, the image must be aligned in memory such that the beginning is found on a word boundary
(the least significant bit of the memory address must be 0).
2. Calculate the number of bytes per scan line.
4 gray shades => 2 bits per pixel
2 bits per pixel => 4 pixels per byte
number of bytes per scan line
3. Determine the display memory location for image 1.
For simplicity, assign the beginning of display memory as the starting address of image 1 (see Figure 14). For the
SDU1352B0x, this address is C000:0000h.
4. Program the Screen 1 Display Start Address Register to point to the beginning of image 1.
Since image 1 is at the beginning of display memory for a 128k system, program the Screen 1 Display Start Address
Register to 0000h.
AUX[06h] = 00h
AUX[07h] = 00h
5. Determine the size of image 1.
vertical size of image 1
display width in pixels
size = ----------------------------------------------------- -
pixels per byte
SED1352
X16-BG-007-04
pixels per scan line
= --------------------------------------------- -
pixels per byte
Screen 1 Display Start Address
Screen 2 Display Start Address
Figure 14: Memory Map for a Dual Panel showing a Single Image
= vertical size of panel 1
× (
number of scan lines in image 1
640
= -------- - = 160 bytes per scan line
4
Display Memory
First half of Image
Second half of Image
number of scan lines in display
= --------------------------------------------------------------------------
2
640
) ×
= -------- - 240
4
Epson Research and Development
Vancouver Design Center
= 00A0h bytes per scan line
480
= -------- - = 240 scan lines
2
= 38400 bytes = 9600h bytes
Programming Notes and Examples
Issue Date: 98/10/08