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Chapter 5: Character LCD Screen
Physically, there are 80 total character locations in DD RAM with 40 characters available
per line. Locations 0x10 through 0x27 and 0x50 through 0x67 can be used to store other
non-display data. Alternatively, these locations can also store characters that can only
displayed using controller's display shifting functions.
The
writing to DD RAM. Write DD RAM data using the
command, and read DD RAM using the
The DD RAM address counter either remains constant after read or write operations, or
auto-increments or auto-decrements by one location, as defined by the I/D set by the
Mode Set
CG ROM
The Character Generator ROM (CG ROM) contains the font bitmap for each of the
predefined characters that the LCD screen can display, shown in
code stored in
the CG ROM. For example, a hexadecimal character code of 0x53 stored in a
location displays the character 'S'. The upper nibble of 0x53 equates to DB[7:4]="0101"
binary and the lower nibble equates to DB[3:0] = "0011" binary. As shown in
character 'S' appears on the screen.
English/Roman characters are stored in CG ROM at their equivalent ASCII code address.
44
Set DD RAM Address
command initializes the address counter before reading or
command.
DD RAM
for each character location subsequently references a position with
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Write Data to CG RAM or DD RAM
Read Data from CG RAM or DD RAM
Figure
Spartan-3E Starter Kit Board User Guide
UG230 (v1.0) March 9, 2006
R
command.
Entry
5-4. The character
DD RAM
Figure
5-4, the
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