HD66730 Datasheet, PDF (18/131 Pages) Hitachi Semiconductor – Dot-Matrix Liquid Crystal Display Controller/Driver Supporting Japanese Kanji, Korean Font Display

HD66730/HD66731
Display Data RAM (DDRAM)
Display data RAM (DDRAM) stores character codes and display attribute codes for displaying data.
A full-size font is displayed using two bytes, and a half-size font is displayed using one byte. Since the
RAM capacity is 80 bytes, 40 full-size characters or 80 half-size characters can be stored.
DDRAM displays only that data stored within the range corresponding to the number of display columns.
Data stored outside the range is ignored. Refer to Combined Display of Full-Size and Half-Size characters
for details on character codes stored in DDRAM. The relationship between DDRAM addresses and LCD
display position depends on the number of display lines (1 line/2 lines/4 lines).
Execution of the display-clear instruction writes H'A0 corresponding to the half-size character for “space”
throughout DDRAM.
Note:
The HD66730/1 performs display by reading character codes from the DDRAM according to the
number of display columns set by the control register. In particular, reading from the DDRAM
begins at the position corresponding to the rightmost character as set by the maximum number of
display columns. This means that one byte of a two-byte full-size character code should not be set
in a position exceeding the maximum number of display columns. For example, do not write a full-
size code (2 bytes) in the 12th and 13th byte when the display is set for six characters.
• 1-line display (NL1/0 = 00)
80 bytes of consecutive addresses from H'00 to H'4F are allocated for DDRAM addresses. When there
are fewer than 40 display characters (at full size), only the number of display characters specified by
NC1/0 are displayed starting from H'00 in the DDRAM. For example, 12 bytes of addresses from H'00
to H'0B are used when a 6-character display (NC1/0 = 00) is performed using one HD66730; addresses
from H'0C on are ignored. In this case, do not write a full-size code into bytes H'0B and H'0C because a
half-size character may be displayed. See Figure 1 for a 1-line display.
• 2-line display (NL1/0 = 01)
The first line in the DDRAM address is displayed for the 40 bytes of addresses from H'00 to H'27, and
the second line is displayed for the 40 bytes of addresses from H'40 to H'67. When there are fewer than
20 display characters (at full size), only the number of display characters specified by NC1/0 will be
displayed starting from the leftmost address of the DDRAM. For example, 24 bytes of addresses from
H'00 to H'0B and H'40 to H'4B are used when a 6-character display (NC1/0 = 00) is performed using
one HD66730. Addresses from H'0C and H'4C on are ignored. See Figure 2 for a 2-line display.
• 4-line display (NL1/0 = 11)
The first line in the DDRAM address is displayed from H'00 to H'13, the second line from H'20 to H'33,
the third line from H'40 to H'53, and the fourth line from H'60 to H'73. For a 6-character display (NC1/0
= 00) (at full-size), only 12 bytes from the leftmost address of DDRAM are displayed. See Figure 3 for
a 4-line display.
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