ra8835 Topway Display, ra8835 Datasheet - Page 50

• Manufacturer Part Number: ra8835
• Description: Dot Matrix Lcd Controller
• Manufacturer: Topway Display

RAiO TECHNOLOGY INC.
Version 1.7
7-14 CG Characteristics
7-15 CG Memory Allocation
7-14-1 Internal Character Generator
7-14-2 External Character Generator ROM
7-14-3 Character Generator RAM
Since the RA8835 series uses 8-bit character codes, it can handle no more than 256 characters at a
time. However, if a wider range of characters is required, character generator memory can be bank-
switched using the CGRAM ADR command.
The internal character generator is recommended for minimum system configurations containing
a RA8835 series, display RAM, LCD panel, single-chip microprocessor and power supply. Since
the internal character generator uses a CMOS mask ROM, it is also recommended for low-power
applications.
The external CG ROM can be used when fonts other than those in the internal ROM are needed.
Data is stored in the external ROM in the same format used in the internal ROM. (See Section
11-4)
The user can freely use the character generator RAM for storing graphics characters. The
character generator RAM can be mapped by the microprocessor anywhere in display memory,
allowing effective use of unused address space.
• 5 x 7-pixel font (See Section 18.)
• 160 JIS standard characters
• Can be mixed with character generator RAM (maximum of 64 CG RAM characters)
• Can be automatically spaced out up to 8 x 16 pixels
• Up to 8 x 8-pixel characters (M2 = 0) or 8 x 16-pixel characters (M2 = 1)
• Up to 256 characters (192 if used together with the internal ROM)
• Mapped into the display memory address space at F000H to F7FFH (M2 = 0) or F000H to
FFFFH (M2 = 1)
• Characters can be up to 8 x 16-pixels; however, excess bits must be set to zero.
• Up to 8 x 8-pixel characters (M2 = 0) or 8 x 16 characters (M2 = 1)
• Up to 256 characters if mapped at F000H to FFFFH (64 if used together with character
generator ROM)
• Can be mapped anywhere in display memory address space if used with the character
generator ROM
• Mapped into the display memory address space at F000H to F7FFH if not used with the
character generator ROM (more than 64 characters are in the CG RAM). Set SAG0 to
F000H and M1 to zero when defining characters number 193 upwards.
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Dot Matrix LCD Controller
www.raio.com.tw
RA8835