Rainbow Electronics HD44780 - Manual (Page 15)

HD44780U
15
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Programming character patterns
This section explains the correspondence between addresses and data used to program character patterns
in EPROM. The HD44780U character generator ROM can generate 208 5
×
8 dot character patterns and
32 5
×
10 dot character patterns for a total of 240 different character patterns.

Character patterns
EPROM address data and character pattern data correspond with each other to form a 5
×
8 or 5
×
10 dot character pattern (Tables 2 and 3).
Table 2 Example of Correspondence between EPROM Address Data and Character Pattern
(5
×
8 Dots)
Data
O 4 O 3 O 2 O 1 O 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 1 0 0 0 1 0
EPROM Address
Character code Line
position
LSB
0 1 0 1
0 1 1 0
0 1 1 1
0 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
1 0 0 0
1 1 0 0 1
1 0 0 0 1
1 0 0 0 1
1 0 0 0 0
1 0 0 0 0
1 0 1 1 0
Cursor position
1 1 1 1 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
A 1 0 A 9 A 8 A 7 A 6 A 5 A 4 A 3 A 2 A 1 A 0 A 1 1
Notes: 1. EPROM addresses A11 to A4 correspond to a character code.
2. EPROM addresses A3 to A0 specify a line position of the character pattern.
3. EPROM data O4 to O0 correspond to character pattern data.
4. EPROM data O5 to O7 must be specified as 0.
5. A lit display position (black) corresponds to a 1.
6. Line 9 and the following lines must be blanked with 0s for a 5
×
8 dot character fonts.