GSM7980 Syntec Semiconductor, GSM7980 Datasheet - Page 9

• Manufacturer Part Number: GSM7980
• Description: Dot Matrix LCD Controller/Driver
• Manufacturer: Syntec Semiconductor

GSM7980
Syntek Semiconductor Co., Ltd.
The character generator ROM generates 5 x 8 dot or 5 x 10 dot character patterns from 8-bit
character codes. It can generate 208 5 x 8 dot character patterns and 32 5 x 10 dot character patterns.
User-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 x 8 dots,
eight character patterns can be written, and for 5 x 10 dots, four character patterns can be written.
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.
Timing Generation Circuit
The timing generation circuit generates timing signals for the operation of internal circuits such as
DDRAM, CGROM and CGRAM. RAM read timing for display and internal operation timing by
MPUaccess are generated separately to avoid interfering with each other. Therefore, when writing
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data to DDRAM, for example, there will be no undesirable interference, such as flickering, in areas
other than the display area.
LCD Driver Circuit
LCD Driver circuit has 16 common and 40 segment signals for LCD driving. Data from
CGRAM/CGROM is transferred to 40 bit segment latch serially, and then it is stored to 40 bit shift
latch. When each common is selected by 16 bit common register, segment data also output through
segment driver from 40 bit segment latch. In case of 1-line display mode, COM1 ~ COM8 have 1/8
duty or COM1 ~ COM11 have 1/11duty , and in 2-line mode, COM1 ~ COM16 have 1/16 duty ratio.
Cursor/Blink Control Circuit
It can generate the cursor or blink in the cursor/blink control circuit. The cursor or the blink appears
in the digit at the display data RAM address set in the address counter.
LCD Controller / Driver
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