HD66724 Datasheet, PDF (34/117 Pages) Hitachi Semiconductor – (Graphics LCD Controller/Driver with Key Scan Function)

HD66724/HD66725
Programming Character Patterns
This section explains the correspondence between addresses and data used to program character patterns in
EPROM.
Programming to EPROM: The HD66724/HD66725 character generator ROM can generate 432 6 × 8-dot
character patterns. Table 17 shows the correspondence between the EPROM address, data, and the
character pattern.
Table 17 Examples of Correspondence between EPROM Address, Data, and Character Pattern
(6 × 8 Dots)
EPROM Address
A₁₂ A₁₁ A₁₀ A₉ A₈ A₇ A₆ A₅ A₄ A₃
0 0 1 0 1 10 0 1 0
0
0
0
0
0
0
0
A₂ A₁ A₀
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
ROM
bit
Character code
0 Line position
Notes: 1. EPROM address: Bit A12 corresponds to the CGROM memory bank switch bit ("ROM").
2. EPROM address: Bits A11 to A4 correspond to a character code.
3. EPROM address: Bits A2 to A0 specify the line position of the character pattern. EPROM
address bit A3 must be set to 0.
4. EPROM data: Bits O5 to O0 correspond to character pattern data.
5. Areas which are lit (indicated by shading) are stored as 1, and unlit areas as 0.
6. 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.
7. 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 HD66724/HD66725 EPROM: Depending on to the user
application, these are handled in either of two ways:
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