FEATURES
•
Interface with either 4-bit or 8-bit
microprocessor.
•
Display data RAM
•
80
×
8 bits (80 characters).
•
Character generator ROM
•
160 different 5
×
7 dot-matrix character
patterns.
•
Character generator RAM
•
8 different user programmed 5
×
7
dot-matrix patterns.
•
Display data RAM and character generator
RAM may be accessed by the
microprocessor.
•
Numerous instructions
•
Clear Display, Cursor Home, Display
ON/OFF, Cursor ON/OFF, Blink Character,
Cursor Shift, Display Shift.
•
Built-in reset circuit is triggered at power
ON.
•
Built-in oscillator.
OVERVIEW
The LCD unit receives character codes (8 bits per
character) from a microprocessor or microcomputer,
latches the codes to its display data RAM (80-byte
DD RAM for storing 80 characters), transforms each
character code into a 5
×
7 dot-matrix character
pattern, and displays the characters on its LCD
screen.
The LCD unit incorporates a character generator
ROM which produces 160 different 5
×
7 dot-matrix
character patterns. The unit also provides a char-
acter generator RAM (64 bytes) through which the
user may define up to eight additional 5
×
7 dot-ma-
trix character patterns, as required by the applica-
tion.
To display a character, positional data is sent via
the data bus from the microprocessor to the LCD
unit, where it is written into the instruction register.
A character code is then sent and written into the
data register. The LCD unit displays the correspond-
ing character pattern in the specified position. The
LCD unit can either increment or decrement the
display position automatically after each character
entry, so that only successive characters codes
need to be entered to display a continuous character
string. The display/cursor shift instruction allows the
entry of characters in either the left-to-right or right-
to-left direction. Since the display data RAM (DD
RAM) and the character generator RAM (CG RAM)
many be accessed by the microprocessor, unused
portions of each RAM may be used as general
purpose data areas. The LCD unit may be operated
with either dual 4-bit or single 8-bit data transers, to
accommodate interfaces with both 4-bit and 8-bit
microprocessors. The low power feature of the LCD
unit will be further appreciated when combined with
a CMOS microprocessor.
Dot-Matrix LCD Units
Display Unit User’s Manual
3
