OPERATING RESTRICTIONS
The LSI (HD44780AXX) used in the LCD units is
reported to have the following defects:
HD44780AXX Defective Functions
1. When the display clear or display/cursor home
instruction is executed when the display has
been shifted from its original position, original
display position may not be restored.
2. When the display/cursor home instruction is
executed, the data in the following display data
RAM locations may be lost.
To counteract these defects. The following re-
strictions should be followed (Table 16).
In the production facility, the LSI device in ques-
tion is now being replaced with a modified version,
HD44780RAXX. The above mentioned restrictions
do not apply to products using the "RA" version of
the LSI. The "RA" version devices have an "R"
printed in the upper, right corner, as shown.
LCD27-37
00 01 02 03 04 05 06 07
41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
00 01 02 03 04 05 06 07
. . .
. . .
1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27
. . .
40 41 42 43 44 45 46 47
5A 5B 5C 5D 5E 5F 60 61 62 63 64 65 66 67
. . .
. . .
. . .
Address HEX
Address HEX
Address HEX
A. Address type a.
B. Address type b and c.
Total: 80 Characters
Total: 40 Characters x 2 Lines
The contents of address locations
23, 27, 63, and 67 may be lost
during the execution of the
display/cursor home instruction.
NOTE: Although address type C is for a single-line display its
address structure is logically the same as for address type b.
The contents of addresses (43), (47), (4B),
and (4F) may be destroyed.
12
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Table 16.
R
HD44780A
Dot-Matrix LCD Units
Display Unit User’s Manual
29