NT3881D ETC-unknow, NT3881D Datasheet - Page 6

• Manufacturer Part Number: NT3881D
• Description: Dot Matrix Lcd Controller And Driver
• Manufacturer: ETC-unknow

Functional Description
The NT3881D is a dot-matrix LCD controller and driver
LSI. It operates with either a 4-bit or an 8-bit
microprocessor (MPU). The NT3881D receives both
instructions and data from the MPU. Some instructions
set operation modes, such as the function mode, data
entry mode, and display mode; as well as some control
LCD display functions, such as clear display, restore
display, shift display, and cursor. Other instructions
include read and write both data and addresses. All
instructions allow users convenient and powerful functions
to control the LCD dot-matrix displays.
Data is written into and read from the Data Display RAM
(DD RAM) or the Character Generator RAM (CG RAM).
As display character codes, the data stored in the DD
RAM decodes a set of dot-matrix character patterns that
are built into the Character Generator ROM (CG ROM).
The CG ROM, with many character patterns (up to 256
patterns), defines the character pattern fonts. The
NT3881D regularly scans the character patterns through
the segment drivers. The CG RAM stores character
pattern fonts at run time if users intend to show character
patterns that are not defined in the CG ROM. This feature
makes character display flexible. Other unused bytes can
be used as general-purpose data storage.
The LCD driver circuit consists of 16 common signal
drivers and 40 segment signal drivers allowing a variety of
application configurations to be implemented. Additionally,
the user can extend display size by cascading the
segment driver LSI NT3882. The maximum display
dimensions can be either 80 characters in a 1-line display
or 40 characters in a 2-line display.
Character Generator ROM (CG ROM)
The character generator ROM generates LCD dot
character patterns from the 8-bit character pattern codes.
The NT3881D provides 3 CG ROM configurations:
1. 192 Characters:
The CG ROM contains 160 5 X 8 dot character patterns
and 32 5 X 10 dot character patterns. An example is the
NT3881D-01, in which the relation between the character
codes and character patterns is shown in Table 1. The
character codes from 00H to 0FH are used to get
character patterns from the CG RAM. Character codes
from 10H to 1FH and from 80H to 9FH map to full
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character patterns. Character codes from E0H to FFH are
assigned to generate 5 X 10 dot character patterns, and
other codes are used to generate 5x8 dot character
patterns.
2. 240 Characters:
The CG ROM contains 192 5 X 8 dot character patterns
and 48 5 X 10 dot character patterns. An example of this
type is the NT3881D-02, in which the relation between the
character codes and character patterns is shown in Table
2.
The character codes from 00H to 0FH are used to get
character patterns from the CG RAM. Character codes
from 10H to 1FH and from E0H to FFH are assigned to
generate 5 X 10 dot character patterns, and other codes
to generate 5 X 8 dot character patterns. No null
character pattern exists in this type. Note that the
underlined cursor, displayed on the 8th duty may be
obscure if the 8th row of a dot character pattern is coded.
We recommend that users display the cursor in the
blinking mode if they code 5x8 dot character patterns is
their custom CG ROM.
3. 256 Characters:
The CG ROM contains 192 5 X 8 dot character patterns
and 64 5 X 10 dot character patterns. No adequate
example is presented here.
The only difference between this type and the just
mentioned second type is that the character codes from
00H to 0FH get character patterns from the CG ROM
rather than from the CG RAM. These character codes are
assigned to generate 5 X 10 dot character patterns. In this
application, the CG RAM would be employed as a
general-purpose data storage.
Custom character patterns are available by mask-
programming ROM. For convenience of character pattern
development, NOVATEK has developed a user-friendly
editor program for the NT3881D to help determine the
character patterns users prefer. By executing the program
on the computer, users can easily create and modify their
character patterns. By transferring the resulting files
generated by the program through a modem or some
other communication method, the user and NOVATEK
have established a reliable, fast link for programming the
CG ROM.
NT3881D
V2.4