Bitmaps And Text Displays - Epson S1D13503 Technical Manual

Page 42

5.2 Bitmaps and Text Displays

For the scope of this guide, a bitmap is a data structure which represents the image shown on the LCD. The bitmap includes
the dimensions of the image, and the color or gray shade palette used to program the lookup table. Text is shown by creating
a font, which in this example is a series of bitmaps, one bitmap per alphanumeric character.
Example 13: Display the word "TEXT" on a 256 color 320 x 240 LCD panel; the Memory Interface is 16
1. Define the font for the letters 'T', 'E', and 'X'.
Each character is 8x8 pixels, with at least one horizontal and vertical side left blank for spacing.
2. Program the lookup table.
See Example 3, "Initialize the Look-Up Table for 256 Colors (Bank 0 Only)," on page 23.
3. Calculate the display memory map.
See Figure 11, "Memory Map Example For 320 x 240 LCD Panel With 256 Colors," on page 39.
4. Write font to display memory.
In a general purpose program the entire bitmapped font would be placed in an array. As characters are to be dis-
played, the program would choose the appropriate bitmap, select the proper position on the screen, and write to dis-
play memory. For this example assume that the program has already selected the proper bitmaps and the correct
positions in display memory (there is a detailed programming example later in this guide; see Section 7.3, "Advanced
Functions" on page 66).
Each highlighted pixel in the text bitmap will be shown at maximum intensity, which is pixel value 0FFh. The text,
for simplicity, will be shown in the upper left corner of the screen. When the program has completed writing the pix-
els for the word "TEXT", the display memory will have the data shown in Figure 15. In this figure the bytes are
grouped within vertical lines.
S1D13503
X18A-G-002-06
Downloaded from Elcodis.com electronic components distributor
bits.
Figure 14: Font For The Message "TEXT"
Epson Research and Development
Vancouver Design Center
Programming Notes and Examples
Issue Date: 01/01/30