HD66710 Datasheet, PDF (17/73 Pages) Hitachi Semiconductor – (Dot Matrix Liquid Crystal Display Controller/Driver)

HD66710
Character Generator ROM (CGROM)
The character generator ROM generates 5 × 8 dot character patterns from 8-bit character codes (Table 3).
It can generate 240 5 × 8 dot character patterns. User-defined character patterns are also available using a
mask-programmed ROM.
Character Generator RAM (CGRAM)
The character generator RAM allows the user to redefine the character patterns. In the case of 5 × 8
characters, up to eight may be redefined.
Write the character codes at the addresses shown as the left column of Table 3 to show the character
patterns stored in CGRAM.
See Table 5 for the relationship between CGRAM addresses and data and display patterns.
Segment RAM (SEGRAM)
The segment RAM (SEGRAM) is used to enable control of segments such as an icon and a mark by the
user program.
For a 1-line display, SEGRAM is read from the COM17 output, and as for 2- or 4-line displays, it is from
the COM33 output, to performs 40-segment display.
As shown in Table 6, bits in SEGRAM corresponding to segments to be displayed are directly set by the
MPU, regardless of the contents of DDRAM and CGRAM.
SEGRAM data is stored in eight bits. The lower six bits control the display of each segment, and the
upper two bits control segment blinking.
Modifying Character Patterns
• Character pattern development procedure
The following operations correspond to the numbers listed in Figure 8:
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 an EPROM.
4. Send the EPROM to Hitachi.
5. Computer processing of the EPROM is performed at Hitachi to create a character pattern listing,
which is sent to the user.
6. If there are no problems within the character pattern listing, a trial LSI is created at Hitachi and
samples 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 will proceed at Hitachi.
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