hd66717 Renesas Electronics Corporation., hd66717 Datasheet - Page 21

• Manufacturer Part Number: hd66717
• Description: Low-power Dot-matrix Liquid Crystal Display Controller/driver -
• Manufacturer: Renesas Electronics Corporation.

Programming Character Patterns
This section explains the correspondence between addresses and data used to program character patterns
in EPROM.
Handling Unused Character Patterns
1. EPROM data outside the character pattern area: This is ignored by the character generator ROM for
2. EPROM data in CGRAM area: Always fill with zeros.
3. Treatment of unused user patterns in the HD66717 EPROM: According to the user application, these
Table 7
Notes: 1. EPROM addresses A11 to A4 correspond to a character code.
Programming to EPROM
The HD66717 character generator ROM can generate 240 5
correspondence between the EPROM address data and the character pattern.
display operation so any data is acceptable.
are handled in either of two ways:
a. When unused character patterns are not programmed: If an unused character code is written into
b. When unused character patterns are programmed as 0s: Nothing is displayed even if unused
DDRAM, all its dots are lit, because the EPROM is filled with 1s after it is erased.
character codes are written into DDRAM. (This is equivalent to a space.)
2. EPROM addresses A2 to A0 specify the line position of the character pattern. EPROM address
3. EPROM data O4 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 should also be programmed. If the
6. EPROM data bits O7 to O5 are invalid. 0 should be written in all bits.
A3 should be set to 0.
eighth raster-row is used for a cursor, this data should all be set to zero.
Example of Correspondence between EPROM Address Data and Character Pattern
(5
8 Dots)
A11
0
A10 A9 A8 A7 A6 A5 A4 A3
1
Character code
0
1
EPROM Address
1
0
0
1
“0”
0
0
0
0
0
0
0
0
Line position
A2 A1 A0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
MSB
8-dot character patterns. Table 7 shows
O4 O3 O2 O1 O0
1
1
1
0 1
0
0
0
0
0 0 0 1
0 0 0 1
0 0 0 1
0 1 0 0
0 1 0 0
0 1 0 0
0 0 0 0
Data
0 1 0
LSB
HD66717
473