HD66727 Datasheet, PDF (28/97 Pages) Hitachi Semiconductor – Low-Power Dot-Matrix Liquid Crystal Display Controller/Driver with Key Scan Function

HD66727
Programming Character Patterns
This section explains the correspondence between addresses and data used to program character patterns in
EPROM.
Programming to EPROM: The HD66727 character generator ROM can generate 240 6 × 8-dot character
patterns. Table 14 shows correspondence between the EPROM address, data, and the character pattern.
Table 14 Example of Correspondence between EPROM Address, Data, and Character Pattern
(6 × 8 Dots)
EPROM Address
A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 A0
0 1 0 1 10 0 1 ⁰
0
0
0
0
0
0
0
000
001
010
011
100
101
110
111
MSB
Data
LSB
O5 O4 O3 O2 O1 O0
0 1 ₀₀₀₁
0 1 0001
0 1 0001
0 01 010
0 0 0100
0 0 0100
0 0 0100
0 0 0000
Character code
0 Line position
Notes: 1. EPROM address bits A11 to A4 correspond to a character code.
2. EPROM address bits A2 to A0 specify the line position of the character pattern. EPROM address
bit A3 must be set to 0.
3. EPROM data bits O5 to O0 correspond to character pattern data.
4. Areas which are lit (indicated by shading) are stored as 1, and unlit areas as 0.
5. The eighth raster-row is also stored in the CGROM, and must also be programmed. If the eighth
raster-row is used for a cursor, this data must all be set to zero.
6. EPROM data bits O7 to O6 are invalid. 0 must be written in all bits.
Handling Unused Character Patterns:
1. EPROM data outside the character pattern area: This is ignored by character generator ROM for display
operation so any data is acceptable.
2. EPROM data in CGRAM area: Always fill with zeros.
3. Treatment of unused user patterns in the HD66727 EPROM: According to the user application, these
are handled in either of two ways:
a. When unused character patterns are not programmed: If an unused character code is written into
DDRAM, all its dots are lit, because the EPROM is filled with 1s after it is erased.
b. When unused character patterns are programmed as 0s: Nothing is displayed even if unused
character codes are written into DDRAM. (This is equivalent to a space.)
28