HD44780 Hitachi Semiconductor (acquired by Renesas), HD44780 Datasheet - Page 13

• Manufacturer Part Number: HD44780
• Description: Dot Matrix Liquid Crystal Display Controller/driver
• Manufacturer: Hitachi Semiconductor (acquired by Renesas)

Character Generator ROM (CGROM)
The character generator ROM generates 5
codes (Table 4). It can generate 208 5
defined character patterns are also available by mask-programmed ROM.
Character Generator RAM (CGRAM)
In the character generator RAM, the user can rewrite character patterns by program. For 5
character patterns can be written, and for 5
Write into DDRAM the character codes at the addresses shown as the left column of Table 4 to show the
character patterns stored in CGRAM.
See Table 5 for the relationship between CGRAM addresses and data and display patterns.
Areas that are not used for display can be used as general data RAM.
Modifying Character Patterns
The following operations correspond to the numbers listed in Figure 7:
1. Determine the correspondence between character codes and character patterns.
2. Create a listing indicating the correspondence between EPROM addresses and data.
3. Program the character patterns into the EPROM.
4. Send the EPROM to Hitachi.
5. Computer processing on the EPROM is performed at Hitachi to create a character pattern listing, which
6. If there are no problems within the character pattern listing, a trial LSI is created at Hitachi and samples
Character pattern development procedure
is sent to the user.
are sent to the user for evaluation. When it is confirmed by the user that the character patterns are
correctly written, mass production of the LSI proceeds at Hitachi.
8 dot character patterns and 32 5
10 dots, four character patterns can be written.
8 dot or 5
10 dot character patterns from 8-bit character
10 dot character patterns. User-
HD44780U
8 dots, eight
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